Conductive particles and method and device for manufacturing the same, anisotropic conductive adhesive and conductive connection structure, and electronic circuit components and method of manufacturing the same

ABSTRACT

An electrical connection is formed by using a double laminated conductive fine particle provided with a conductive metal layer on the surface of a spherical elastic base particle by electroless plating and electroplating and a layer of a low-melting-point-metal on the surface of the conductive metal layer and wherein the conductive metal layer comprise a plurality of metal layers.

FIELD OF THE INVENTION

The present invention relates to a manufacturing method of conductivefine particles which are free from aggregation in a plating solution andwhich forms a plating layer having a extremely uniform thickness, themanufacturing device thereof, the conductive fine particles as well asan anisotropic conductive adhesive and a conductive connectingstructural element using such particles.

The present invention further concerns an electronic circuit part whichis obtained by connecting an electronic circuit element, such as asemiconductor element, a quartz oscillator and a photoelectric transferelement that are used in the field of electronics, and an electroniccircuit substrate through conductive fine particles in a manner so as tobe connected to fine electrodes, an electronic circuit element, anelectronic circuit substrate and conductive fine particles used in suchan electronic circuit part, as well as a manufacturing method for suchan electronic circuit part.

BACKGROUND OF THE INVENTION

Conductive materials include conductive paste, conductive adhesives,anisotropic conductive films, etc., and for this conductive material, aconductive composition comprising conductive fine particles and a resinis used. With respect to the conductive fine particles, there aregenerally used metal powder, carbon powder, fine particles having ametal plating layer on the surface, etc.

Manufacturing methods for such conductive fine particles having a metalplating layer on the surface are disclosed by for example, the followingJapanese Kokai Applications: Sho-52-147797, Sho-61-277104,Sho-61-277105, Sho-62-185749, Sho-63-190204, Hei-1-225776, Hei-1-247501and Hei-4-147513.

Among these manufacturing methods, when carrying out plating on fineparticles having a particle size of not less than 5000 μm, barrelplating devices are generally used. In the barrel plating device, aplating target is put inside a rotatable barrel having a polygoncylinder shape in which a plating solution is contained, and while thebarrel is being rotated, electroplating is carried out by allowing theplating target to contact the cathode placed inside the barrel.

However, when plating is carried out on fine particles having a particlesize not more than 5000 μm by a method using the barrel plating device,problems arise in it that fine particles in an aggregated state aresubjected to plating in the plating solution, failing to formmono-particles and in it that particles are not plated uniformly,causing an irregular plating layer.

In order to solve these problems, for example, the following platingdevices have been proposed: Japanese Kokai Publication Hei-7-118896discloses a manufacturing device for conductive fine particles whichcomprises a disk-shaped bottom plate secured to the upper end of aperpendicular driving shaft, a contact ring for conducting electricityplaced on the upper face of the porous member, a porous member that isplaced in the vicinity of the contact ring and that allows only aplating solution to pass there through, a hollow cover of a trapezoidalcone shape having an opening on its upper center portion, a treatmentchamber formed in a manner so as to sandwich the contact ring betweenthe outer circumferential portion of the hollow cover and the bottomplate, a supply tube for supplying the plating solution to the treatmentchamber through the opening, a container for receiving plating solutionscattered from the pores of the porous member, a drain tube for drainingthe plating solution accumulated in the container, and an electrodeinserted through the opening to contact the plating solution, wherein,during the plating process, rotation and stoppage or speed reduction arerepeated.

Japanese Kokai Publication Hei-8-239799 discloses a manufacturing devicefor conductive fine particles, in which the contact ring and the porousmember are integrally connected.

Japanese Kokai Publication Hei-9-137289 discloses a manufacturing methodfor conductive fine particles, wherein a plating device, comprising arotatable plating device main body having a filter section formed on atleast one portion of its outer circumferential section and a cathode asa contact ring formed on the outer circumferential section and an anodeplaced inside the main body so as not to contact the cathode, is usedfor forming a plating layer on the surface of the fine particles putinside the main body, while the main body is rotated centered on itsrotation axis and the plating solution is supplied to inside of the mainbody.

In these manufacturing devices for conductive fine particles, a platingtarget is pressed onto the contact ring by a centrifugal force, androtated, and stopped or reduced in the speed repeatedly, therefore, theconductivity is improved even in the uniformly mixed state, the currentdensity is increased, and the update of the plating solution isfrequently carried out so that the fine particles are free fromaggregation in the plating solution, thereby making it possible toobtain conductive fine particles having a plating layer with a uniformthickness.

However, the following problems arise in these manufacturing devices forconductive fine particles.

The pore size of the porous member and the number of revolutions(peripheral velocity) of the treatment chamber are appropriatelyselected in accordance with the particle size of fine particles asplating targets. In the case when fine particles having a particle sizeof not more than 100 μm are subjected to plating, it is necessary toincrease the peripheral velocity of the treatment chamber so as to makethe particles contact the contact ring. For example, in the case of fineparticles having a diameter in the range of 60 to 100 μm, the pore sizeof the porous member needs to be set to not less than 20 μm and theperipheral velocity needs to be set to not less than 300 m/min. It isconfirmed that the peripheral velocity not more than this value is hardto allow the fine particles to contact the cathode (contact ring) andplating deposition is sometimes not carried out.

However, when the peripheral velocity of the treatment chamber isincreased, the plating solution is subject to a force in the outercircumferential direction by the function of a centrifugal force so thatthe plating solution forms a vortex having a mortar-like shape insidethe treatment chamber, gradually rises along the inner wall of thehollow cover, and is scattered from the opening of the hollow cover. Asa result, the problem arises in it that the fine particles flow out(overflow) from the treatment chamber together with the scatteredplating solution. In addition, if the amount of the liquid within thetreatment chamber is reduced so as to prevent the overflow, the area inwhich the electrode in contact with the plating solution is reduced,with the result that the current density is reduced and further theformation of a vortex causes the electrode to be exposed, resulting inno contact with the plating solution and no current flow.

Because of these problems, it have been impossible to actually carry outplating on fine particles of not more than 100 μM.

Moreover, with respect to the pore size of the porous member, those poresizes not allowing a plating solution to pass there through have beenadopted, and several kinds of porous members have been used inaccordance with the particle size of the fine particles.

However, since these porous members are filter-shaped porous membersmade of plastics or ceramics having communicating bubbles, the poresizes within the porous members have considerably much variation. Forthis reason, at portions where the pore sizes of the porous members arethe same as or greater than the particle size of the fine particles,clogging and particle losses occur at the time of passage of theparticles. Moreover, when a porous member of not more than 20 μm isused, the resistance at the time of the passage of the plating solutionthrough the porous member becomes greater, as a result that the amountof passage of the plating solution through the porous member isremarkably reduced. When clogging occurs in this state, the platingsolution within the treatment chamber is hardly circulated and/orupdated, with the result that problems such as a liquid temperature risewithin the treatment chamber and variations in the composition of theplating solution occur, causing serious adverse effects on the qualityof the plating layer.

Moreover, in the case of these prior art manufacturing devices forconductive fine particles, it has been confirmed that, whenelectroplating is carried out on fine particles of approximately notmore than 100 μm, aggregation occurs as the electroplating progresses,and there is a limit in efficiently carrying out electroplating on eachof the fine particles.

In prior art manufacturing methods for conductive fine particles, anelectric current is applied and electroplating is carried out in a statewhere the fine particles is being pressed against the contact ring(cathode) by the function of a centrifugal force due to rotation of thetreatment chamber. Here, at the time of stoppage of the powerapplication, the rotation is also stopped, with the result that the fineparticles are dragged by gravity and the flow of the plating solutiondue to inertia, made to drop on the flat surface of the central portionof the bottom plate, and mixed. When the treatment chamber is rotatednext time, they are pressed against the contact ring in a differentattitude while being mixed, and subjected to electroplating. By usingthis repeated cycle of rotation and stoppage, an attempt is made to forma plating layer having a uniform thickness on each of the fine particlescontained in the treatment chamber.

However, in this conventional manufacturing method for conductive fineparticles, the following problems arise.

In the conventional manufacturing method for conductive fine particles,a given time is provided from the start of rotation of the treatmentchamber to the start of the application of power, and during this time,the fine particles are shifted to the contact ring (cathode)(hereinafter, this time is referred to as “particle shifting time”).Next, the power application is started while the treatment chamber isbeing rotated at a constant speed, an electric current is applied to thefine-particle lumps contacting the contact ring, so that a plating coatfilm is deposited (hereinafter, this time is referred to as “powerapplication time”). Further, at the time of the stoppage of the powerapplication, the rotation speed of the treatment chamber is reducedgradually in a predetermined time (hereinafter, this time is referred toas “speed reduction time”) so that the treatment chamber is temporarilystopped (hereinafter, this time is referred to as “stoppage time”). Theprocess is repeated with this cycle as one cycle.

In this case, in order to improve the efficiency of plating, it isnecessary to set the power application time longer or to increase thecurrent density at the time of power application.

However, since the fine particles are allowed to contact the contactring (cathode) in a state of aggregated fine-particle lumps, when aplating coat film is deposited in this state by applying power for along time, some particles are subjected to plating in the aggregatedstate, as a result to occur a problem of aggregation lumps. In otherwords, in order to prevent the occurrence of aggregation lumps, thepower application time cannot be set much longer.

Moreover, when the current density is increased higher, the amount ofdeposition of the plating coat film becomes too high within the powerapplication time in one cycle, as a result to occur in a problem ofaggregation lumps. This is presumedly because the too much amount ofdeposition of the plating coat film in one cycle causes a deposition ofa thick plating coat film covering the surface of aggregatedfine-particle lumps, thus, it is not possible to break the plating coatfilm covering the surface of fine-particle lumps by using only astirring force at the time of the stoppage of the treatment chamber, andanother plating coat film is again deposited on the surface thereof atthe next power application.

Furthermore, the following problems arise in the prior art manufacturingmethods for conductive fine particles. In the case when plating iscarried out on fine particles having a small specific gravity, sincethere is little difference between their specific gravity and thespecific gravity of the plating solution, there is a delay in theirapproach to the contact ring, and when power is applied before they havecompletely approached the contact ring, the conductive base layer tendsto melt down due to the bipolar phenomenon. The bipolar phenomenonrefers to a phenomenon in which in the case when contact force betweenthe plating target and the cathode is weak, or in the case when power isapplied before the plating target has contacted the cathode, the platingtarget itself is subjected to polarization, and the coat film melts downfrom portions getting positively charged.

In particular, in the case of fine particles to which electricconductivity is imparted by forming a conductive base layer of angstromson the surface of the non-conductive fine particles, such as organicresin fine particles and inorganic fine particles, by using theelectroless plating method, etc., when the bipolar phenomenon occurs,the conductive base layer melts down and the fine particle surface losesits conductivity, failing to carry out electroplating.

Moreover, in the case when the power application time is too short,since the application of power is started before all the fine particleshave approached the contact ring, the bipolar phenomenon occurs, failingto carry out electroplating. In contrast, when the power application istoo long, the ratio of the power application time within one cyclebecomes smaller, resulting in degradation in the efficiency.

Here, anisotropic conductive adhesives have been widely used so as toelectrically connect small-size parts such as semiconductor elements toa substrate, or to electrically connect substrates with each other, inthe field of electronics products such as liquid crystal displays,personnel computers and portable communication devices.

With respect to these anisotropic conductive adhesives, binder resins inwhich conductive fine particles are blended have been widely used. Withrespect to such conductive fine particles, those particles made byapplying metal plating onto the outer surface of organic base particlesor inorganic base particles have been widely used. With respect to theseconductive fine particles, various techniques have been disclosed, forexample, by Japanese Kokoku Publications Hei-6-9677, Japanese KokaiPublication Hei-4-36902, Hei-4-269720 and Hei-3-257710.

Moreover, with respect to anisotropic conductive adhesives in whichthese conductive fine particles are blended in binder resins so as toform films and paste, various techniques have been disclosed by forexample, Japanese Kokai Publications Sho-63-231889, Hei-4-259766,Hei-2-291807, and Hei-5-75250.

In anisotropic conductive adhesives based on these techniques, thoseadhesives that use conductive fine particles comprising a conductivelayer on an electric insulating material by electroless plating havebeen widely adopted. However, the conductive layer formed by electrolessplating generally cannot be made thicker, resulting in a problem oflittle current capacity at the time of connection.

For this reason, in an attempt to ensure the conductivity and toincrease the current capacity at the time of connection, plating bynoble metal has been adopted, however, since it is difficult to directlyplate the noble metal on an insulating material, a method in which basemetal such as nickel is first plated by electroless plating, and noblemetal is then substitute-plated has been adopted. In the substitutionreaction in this case, the surface of the base metal layer is notcompletely substituted, and a part of the base metal remains, thereforethere is a possibility that this part gradually deteriorates, failing toprovide sufficient reliability.

In particular, in recent years, miniaturization has been achieved inelectronic apparatuses and electronic parts, with the result that wiringfor substrates, etc., becomes finer and reliability in connectingsections has been demanded acutely. Moreover, with respect to elementsto be adopted for plasma displays that have been developed recently,since these elements are of the large-current driven type, anisotropicconductive adhesives which are suitable for large electric currents havebeen demanded. In order to solve the problem with current capacity,there is another method to increase the concentration of the conductivefine particles, however, an increased concentration causes anotherproblem of the possibility of leakage between electrodes.

Meanwhile, electronic circuit elements, such as semiconductor elements,quartz oscillators, and photoelectric transfer elements, are connectedto an electronic circuit substrate to form an electric circuit part,thus, these are utilized in various forms in the field of electronics.Various techniques have been developed with respect to connection ofthese electronic circuit elements to electronic circuit substrates.

Japanese Kokai Publication Hei-9-293753 has disclosed a technique inwhich a conductive ball is used in order to improve the connectingproperty of an electronic circuit element and an electronic circuitsubstrate without applying any specific additional process to therespective electrode sections. However, this technique fails to solvethe following various problems systematically.

Japanese Kokai Publication Hei-9-213741 discloses a semiconductor devicewherein a semiconductor chip and an organic printed wiring substrate areconnected with each other by solder and the entire surface, etc. of theconnected section is coated with an insulating organic sealing material.However, this technique requires time-consuming tasks, and also fails tosolve various problems with connecting sections systematically.

Upon manufacturing an electronic circuit part by connecting electroniccircuit elements to an electronic circuit substrate, various problemsarise due to the connecting property of the connecting section, andvarious techniques have been used so as to solve these problems.

Here, these prior art techniques are collectively described as followsby exemplifying a case in which an IC bear chip as a semiconductorelement is connected to an electronic circuit substrate.

(1) Wire Bonding Method

Peripheral electrodes of the IC chip and the electronic circuitsubstrate are heated and press-bonded by using thin wires of gold orcopper so as to connect to each other. This wire bonding method has anadvantage in that wire connection is made without applying anyprocessing to aluminum electrodes in the IC chips, however, in contrast,it has disadvantages in that the connecting pitch is not made smallerand in that the connecting section becomes bulky.

(2) Flip Chip Bonding Method by Using Solder Bumps (for Example,Japanese Kokai Publication Hei-9-246319)

Solder bumps are formed on the electrode sections of the IC bear chip,and are superposed on the electrode sections of the electronic circuitsubstrate, and heated so that connection is formed by molten solder(FIG. 36). The formation of solder bumps is made by a method in whichafter forming a multi-layer metal barrier layer on the aluminumelectrodes of the IC chip, solder plating is carried out and thenheated, or in which solder balls are placed on the electrode sections,and then heated.

The flip chip bonding method by solder bumps has an advantage in thatpositioning between the electrodes is easily carried out because of theself-alignment effect of the solder. In contrast, problems arise in itthat a multi-layer metal barrier layer has to be formed on the aluminumelectrodes of the IC chip, that the gap cannot be maintained constantdue to molten solder bump sections, and that the solder bump sectionsare subjected to “shearing deformation” exerted by the difference in thethermal expansion coefficient between the IC bear chip and theelectronic circuit substrate, with the result that cracks tend to occurin the connected section between the solder bump sections and thesubstrate electrode sections, resulting in degradation in the connectingreliability.

(3) Flip Chip Bonding Method by Using a Solder Coat Ball Having a HighlyRigid Core (for Example, Japanese Kokai Publications Hei-9-293753,Hei-9-293754, Hei-5-243332), Hei-7-212017)

For example, balls coated coating copper core with solder are placed onthe electrode sections on an IC chip, and then heated so that the soldercoat balls are secured to the electrode sections on the IC chip; then,the secured solder coat balls are superposed on the electrode sectionsof an electronic circuit substrate, and then again heated so as to makeconnection (FIG. 47). In the same manner as (2), in this method also,“shearing deformation” is exerted due to the difference in the thermalexpansion coefficient between the IC bear chip and the electroniccircuit substrate, with the result that cracks tend to occur in theconnected sections between the solder coat balls and the substrateelectrode sections, resulting in degradation in the connectingreliability.

(4) Flip Chip Bonding Method by the Bump Transfer Method

A gold bump formed on a bump forming substrate is transferred and placedon a lead portion of a tin- or gold-plated film carrier formed bythermal press bonding at the first stage, and next, after an IC chip hasbeen superposed thereon, the second srage thermal press bonding iscarried out (FIG. 48). This method has an advantage in that theformation of metal barrier layer is not required on the aluminumelectrodes on the IC chip. In contrast, a particularly high pressureneeds to be applied at the second stage thermal press bonding, resultingin a possibility of damage to the IC chip performance.

(5) Flip Chip Bonding Method by Using Bumps Comprising Conductive Resin

A conductive resin comprising silver powder and an epoxy-based adhesiveis formed into a bump shape with a thickness of approximately 10 μm by ascreen printing method on the electrode sections of an IC bear chip, andthis is heated to be cured, and after being superposed on the electrodesections of an electronic circuit substrate, connection is performed byusing another conductive adhesive (FIG. 49). This method has advantagesin that upon connection, no expensive materials are required while onlya simple process is used. In contrast, problems arise in that specialelectrodes, made of nickel/palladium, etc., have to be added to thealuminum electrodes of the IC chip, and in that the bump section issusceptible to plastic deformation, with the result that the connectionreliability may deteriorate.

(6) Flip Chip Bonding Method by an Anisotropic Conductive Adhesive

Metal fine particles of approximately 5 μm, or conductive fine particlesapplying metal plating to resin core fine particles, are blended with athermoplastic or thermosetting adhering resin to form a liquid or afilm-shaped anisotropic conductive adhesive, and by using thisanisotropic conductive adhesive, gold bump sections formed on thealuminum electrodes of an IC chip and the electrode sections of anelectronic circuit substrate are joined to each other by thermal pressbonding (FIG. 50). This method has an advantage in that upon joining, noreinforcing seal resin, which is required in the above-mentioned (1) to(5), for filling the gap between the IC chip and the electronic circuitsubstrate is required. In contrast, because of the necessity ofinstalling the gold bump, problems arise in that the conductive fineparticles enter the gap section other than the gap between the IC chipand the electrode sections of the electronic circuit substrate,resulting in a reduction in the insulating resistivity between adjacentelectrodes and the subsequent possibility of a short circuit between theelectrodes.

In order to solve the above-mentioned problems with the prior arttechniques (1) to (6), the following devises are proposed:

In the wire bonding method (1) and the flip chip bonding method by usingsolder bumps (2), in order to solve the problem of the difficulty inhigh-density packaging with pitches of not more than 100 μm, an attemptis required to join an IC chip with high density wiring to an electroniccircuit substrate.

In the flip chip bonding method by solder bumps (2) and the flip chipbonding method by using a solder coat ball having a highly rigid core(3), in order to solve the problems in which shearing deformation isexerted due to the difference in the thermal expansion coefficientbetween the IC chip and the electronic circuit substrate with the resultthat cracks tend to occur in the connected sections between the solderbumps or the solder coat balls and the substrate electrode sections,resulting in degradation in the connecting reliability, and in order tosolve the problem in which, in the flip chip bonding method by bumpsmade of conductive resin (5), the bump section is susceptible to plasticdeformation with the result that the connection reliability maydeteriorate, an attempt is required to improve the connectionreliability in the electronic circuit parts comprising IC chips andelectronic circuit substrates.

In the filp chip bonding method by the use of the bump transfer method(4), in order to solve the problem in which a particularly high pressureneeds to be applied at the second stage thermal press bonding, resultingin a possibility of damage to the IC chip performance, an attempt isrequired to eliminate the need for applying a high pressure in theattaching process between the IC chip and the electronic circuitsubstrate.

In the flip chip bonding method by an anisotropic conductive adhesive(6), in order to solve the problem in which the conductive fineparticles enter the gap section other than the gap of the electrodesections with the result that the insulating resistivity between theadjacent electrodes is reduced, an attempt is required to prevent thereduction in the insulating resistivity between the adjacent electrodesof the IC chip and electronic circuit substrate.

In order to solve the problems with the prior art, attempts have beenrequired to solve all the above-mentioned problems.

SUMMARY OF THE INVENTION

In the light of the above-mentioned problem, the present invention hasits object to provide a manufacturing device for conductive fineparticles which can carry out a plating process efficiently and can forma uniform plating layer on fine particles of not more than 100 μm.

Moreover, another objective of the present invention is to provide amanufacturing device for conductive fine particles which can preventaggregation of conductive fine particles and can form an electroplatinglayer uniformly on the surface of each of the conductive fine particles.

Furthermore, still another objective of the present invention is toprovide a manufacturing method for conductive fine particles which canform a plating layer having a uniform thickness on each of the fineparticles efficiently without causing aggregation of the fine particlesin a plating solution.

Still another objective of the present invention is to provide ananisotropic conductive adhesive and a conductive connecting elementwhich have a low connecting resistance, have a large current capacityupon connection, have high connecting reliability and is free fromleakage, and also to provide conductive fine particles used for suchpurposes.

The other objective of the present invention is to provide an electroniccircuit part which can systematically eliminate malconnection, etc.between an electronic circuit element and an electronic circuitsubstrate resulting from various reasons, and an electronic circuitelement, an electronic circuit substrate and conductive fine particlesused for such an electronic circuit part, as well as a manufacturingmethod for such an electronic circuit part.

The present invention 1 provides a manufacturing device for conductivefine particles which comprises: a disk-shaped bottom plate secured tothe upper end of a perpendicular driving shaft; a porous member that isplaced on the outer circumferential upper face of the bottom plate andthat allows only a plating solution to pass there through; a contactring for conducting electricity placed on the upper face of the porousmember; a hollow cover of a trapezoidal cone shape having an opening onits upper center portion, to the upper end of which a hollow cylinderhaving the same pore diameter as the opening diameter is joined, withthe upper end of the hollow cylinder being bent toward the inner wallside of the hollow cylinder; a rotatable treatment chamber formed in amanner so as to sandwich the porous member and the contact ring betweenthe outer circumferential portion of the hollow cover and the bottomplate; a supply tube for supplying the plating the solution to thetreatment chamber through the opening; a container for receiving platingsolution scattered from the pores of the porous member; a drain tube fordraining the plating solution accumulated in the container, and anelectrode inserted through the opening to contact the plating solution.

The present invention 2 provides a manufacturing device for conductivefine particles which comprises: a disk-shaped bottom plate secured tothe upper end of a perpendicular driving shaft; a porous member that isplaced on the outer circumferential upper face of the bottom plate andthat comprises a plate-shaped porous support and a sheet-shaped filter,affixed on inner side face thereof, having a thickness of 10 to 1000 μmwith a pore size allowing only a plating solution to pass there through;a contact ring for conducting electricity placed on the upper face ofthe porous member; a hollow cover of a trapezoidal cone shape having anopening on its upper center portion, a rotatable treatment chamberformed in a manner so as to sandwich the porous member and the contactring between the outer circumferential portion of the hollow cover andthe bottom plate; a supply tube for supplying the plating solution tothe treatment chamber through the opening; a container for receiving theplating solution scattered from the pores of the porous member; a draintube for draining the plating solution accumulated in the container, andan electrode inserted through the opening to contact the platingsolution.

The present invention 3 provides a manufacturing device for conductivefine particles having the same construction as the manufacturing devicefor conductive fine particles of the present invention 1 except that theporous member comprises a plate-shaped porous support and a sheet-shapedfilter, affixed on inner side face thereof, having a thickness of 10 to1000 μm with a pore size allowing only a plating solution to pass therethrough.

The present invention 4 provides a manufacturing device for conductivefine particles which comprises: a disk-shaped bottom plate secured tothe upper end of a perpendicular driving shaft; a plate-shaped porousmember that allows only a plating solution to pass there through andthat is placed on the upper face of the bottom plate; a contact ring forconducting electricity placed on the upper face of the porous member; ahollow cover of a trapezoidal cone shape having an opening on its uppercenter portion; a rotatable treatment chamber formed in a manner so asto sandwich the porous member and the contact ring between the outercircumferential portion of the hollow cover and the bottom plate; asupply tube for supplying the plating solution to the treatment chamberthrough the opening; a container for the receiving plating solutionscattered from the pores of the porous member; a drain tube for drainingthe plating solution accumulated in the container, and an electrodeinserted through the opening to contact the plating solution.

The present invention 5 provides a manufacturing device for conductivefine particles which comprises: a disk-shaped bottom plate secured tothe upper end of a perpendicular driving shaft; a plate-shaped porousmember that allows only a plating solution to pass there through andthat is placed on the upper face of the bottom plate; a contact ring forconducting electricity placed on the upper face of the porous member; ahollow cover of a trapezoidal cone shape having an opening on its uppercenter portion, to the upper end of which a hollow cylinder having thesame pore diameter as the opening diameter is joined, with the upper endof the hollow cylinder being bent toward the inner wall side of thehollow cylinder; a rotatable treatment chamber formed in a manner so asto sandwich the porous member and the contact ring between the outercircumferential portion of the hollow cover and the bottom plate; asupply tube for supplying the plating solution to the treatment chamberthrough the opening; a container for receiving the plating solutionscattered from the pores of the porous member; a drain tube for drainingthe plating solution accumulated in the container, and an electrodeinserted through the opening to contact the plating solution.

The present invention 6 provides a manufacturing device for conductivefine particles having the same construction as the manufacturing devicefor conductive fine particles of the present invention 4 or 5 exceptthat the porous member comprises a plate-shaped porous support and asheet-shaped filter, affixed on upper face thereof, having a thicknessof 10 to 1000 μm with a pore size allowing only a plating solution topass there through.

The present invention 7 provides a manufacturing method for conductivefine particles which comprises a plating process providing anelectroplating layer on the surface of each of the fine particles, and aprocess of applying at least one kind of force selected from the groupconsisting of a shearing force, an impact force and cavitation in orderto disperse, pulverize and divide into individual particles, aggregatedlumps of fine particles formed during the plating process.

The present invention 8 provides a manufacturing method for conductivefine particles which comprises a plating process for making the fineparticles collide with a cathode by a centrifugal force in a platingbath having the cathode and an anode to form an electroplating layer onthe surface of each of the fine particles, and a process of applying atleast one kind of force selected from the group consisting of a shearingforce, an impact force and cavitation in order to disperse, pulverizeand divide into individual particles, aggregated lumps of fine particlesformed during the plating process.

The present invention 9 provides a manufacturing method for conductivefine particles, which comprises loading pre-treated fine particles intoa treatment chamber, and carrying out a plating process by allowing thetreatment chamber to rotate centered on its rotation axis whilesupplying a plating solution into the treatment chamber to form anelectroplating layer on each of the fine particles, and a step ofapplying at least one kind of force selected from the group consistingof a shearing force, an impact force and cavitation in order todisperse, pulverize and divide into individual particles, aggregatedlumps of fine particles formed during the plating process, wherein theplating process is performed with use of an electroplating devicecomprising: a disk-shaped bottom plate secured to the upper end of aperpendicular driving shaft; a porous member that is placed on the outercircumferential upper face of the bottom plate and that allows only aplating solution to pass there through; a contact ring for conductingelectricity placed on the upper face of the porous member; a hollowcover of a trapezoidal cone shape having an opening on its upper centerportion, to the upper end of which a hollow cylinder having the samepore diameter as the opening diameter is joined, with the upper end ofthe hollow cylinder being bent toward the inner wall side of the hollowcylinder; a rotatable treatment chamber formed in a manner so as tosandwich the porous member and the contact ring between the outercircumferential portion of the hollow cover and the bottom plate; asupply tube for supplying the plating solution to the treatment chamberthrough the opening; a container for receiving the plating solutionscattered from the pores of the porous member; a drain tube for drainingthe plating solution accumulated in the container, and an electrodeinserted through the opening to contact the plating solution.

The present invention 10 provides a manufacturing device for conductivefine particles used for carrying out the manufacturing method forconductive fine particles of the present inventions 7, 8 and 9.

The present invention 11 provides a manufacturing method for conductivefine particles which comprises: a disk-shaped bottom plate secured tothe upper end of a perpendicular driving shaft; a porous member that isplaced on the outer circumferential upper face of the bottom plate andthat allows only a plating solution to pass there through; a contactring for conducting electricity placed on the upper face of the porousmember; a hollow cover having an opening on its upper center portion; arotatable plating vessel formed in a manner so as to sandwich the porousmember and the contact ring between the outer circumferential portion ofthe hollow cover and the bottom plate; a treatment chamber, placedinside the plating vessel, that is formed by a partition plate allowingonly a plating solution to pass there through, and that includes theinside face of the contact ring; a supply tube for supplying the platingsolution to the plating vessel through the opening; a container forreceiving the plating solution scattered from the pores of the porousmember; a drain tube for draining the plating solution accumulated inthe container, and an electrode inserted through the opening to contactthe plating solution.

The present invention 12 provides a manufacturing method for conductivefine particles for forming a plating layer on the surface of each of thefine particles by a plating process, which comprises a power applicationprocess for applying power with the fine particles contacting thecathode to form a plating layer on the surface of each of the fineparticles and a stirring process for stirring the fine particles,wherein said plating process is performed with use of a manufacturingdevice for conductive fine particles that comprising; a rotatabletreatment chamber that has a cathode on its side face and a filtersection allowing the plating solution to pass there through and to drainit; and an anode placed in the treatment chamber so as not to contactthe cathode, is carried out by repeating rotation and stoppage of thetreatment chamber.

The present invention 13 provides a manufacturing method for conductivefine particles for forming an electroplating layer on the surface ofeach of the fine particles by a plating process, wherein the platingprocess, using a manufacturing device for conductive fine particlescomprising a rotatable treatment chamber having a cathode on its sideface and a filter section passing the plating solution to drain it, andan anode placed in the treatment chamber so as not to contact thecathode, comprises steps of applying power with the fine particles beingmade contact with the cathode by the effect of a centrifugal forcecaused by the rotation of the treatment chamber to form anelectroplating layer on the surface of each of the fine particles, andstopping the rotation of the treatment chamber and the application ofpower, further repeating the rotation and stoppage of the treatmentchamber, and wherein the difference in gravity between the fineparticles and the plating solution is set in the range of 0.04 to 22.00.

The present invention 14 provides a manufacturing method for conductivefine particles for forming an electroplating layer on the surface ofeach of the fine particles by a plating process, wherein the platingprocess, using a manufacturing device for conductive fine particles thatcomprises; a rotatable treatment chamber that has a cathode on its sideface and a filter section allowing the plating solution to pass therethrough and to drain it; and an anode placed in the treatment chamber soas not to contact the cathode, comprises the steps of applying powerwith the fine particles being made contact with the cathode by theeffect of a centrifugal force caused by the rotation of the treatmentchamber, so as to form an electroplating layer on the surface of each ofthe fine particles, and stopping the rotation of the treatment chamberand the application of power, and repeating the rotation and stoppage ofthe treatment chamber, wherein the rotation of the treatment chamber iscarried out with the number of revolutions so as to set the centrifugaleffect at 2.0 to 40.0, the power application is started 0.5 to 10seconds after the start of the rotation of the treatment chamber, andthe time of stoppage of the treatment chamber is set to 0 to 10 seconds.

The present invention 16 provides conductive fine particle, which issubjected to electroplating on the outer surface thereof, wherein aparticle size thereof is 0.5 to 500 μm, an aspect ratio of less than 1.5and a variation coefficient of not more than 50%, and an anisotropicconductive adhesive and a conductive connecting element that use suchconductive fine particles.

The present invention 17 provides an electronic circuit part which isformed by electrically connecting an electrode section of an electroniccircuit element and an electrode section of an electronic circuitsubstrate,

wherein the connection is formed by using a laminated conductive fineparticle provided with a conductive metal layer on the surface of aspherical elastic base particle, and

the electrical connection is formed by a plurality of the laminatedconductive fine particles per each connecting section at connectingsections between the electrode section of the electronic circuit elementand the electrode section of the electronic circuit substrate.

BRIEF DESCRIPTIONS OF THE DRAWINGS

FIG. 1 is a schematic cross-sectional view that shows a manufacturingdevice for conductive fine particles of the present invention.

FIG. 2 is a schematic cross-sectional view that shows a conventionalmanufacturing device for conductive fine particles.

FIG. 3 is a schematic enlarged view that shows a hollow cover in oneembodiment of the manufacturing device for conductive fine particles ofthe present invention.

FIG. 4 is a schematic enlarged view that shows a hollow cover in oneembodiment of the manufacturing device for conductive fine particles ofthe present invention.

FIG. 5 is a schematic enlarged view that shows a hollow cover in oneembodiment of the manufacturing device for conductive fine particles ofthe present invention.

FIG. 6 is a schematic enlarged view that shows a hollow cover in oneembodiment of the manufacturing device for conductive fine particles ofthe present invention.

FIG. 7 is a schematic cross-sectional view that shows a treatmentchamber sealing type in one embodiment of the manufacturing device forconductive fine particles of the present invention.

FIG. 8 is a schematic enlarged view of a porous member in one embodimentof the manufacturing device for conductive fine particles of the presentinvention.

FIG. 9 is a schematic cross-sectional view that shows one embodiment ofthe manufacturing device for conductive fine particles in the presentinvention.

FIG. 10 is a schematic cross-sectional view that shows one embodiment ofthe manufacturing device for conductive fine particles in the presentinvention.

FIG. 11 is a schematic cross-sectional view that shows one embodiment ofthe manufacturing device for conductive fine particles in the presentinvention.

FIG. 12 is a schematic cross-sectional view that shows one embodiment ofthe manufacturing device for conductive fine particles in the presentinvention.

FIG. 13 is a system flow diagram of a high-pressure homogenizer inExample 10.

FIG. 14 is a flow diagram inside the chamber of the high-pressurehomogenizer in Example 10.

FIG. 15 is a flow diagram showing a circulation type in which anelectroplating device of Example 15 and a pulverizing device(high-pressure homogenizer) are combined.

FIG. 16 is a flow diagram showing a circulation type in which anelectroplating device of Example 16 and a pulverizing device (highpressure homomixer) are combined.

FIG. 17 is a flow diagram showing a circulation type in which anelectroplating device of Example 17 and a pulverizing device (staticmixer) are combined.

FIG. 18 is a flow diagram showing a circulation type in which anelectroplating device of Example 18 and a pulverizing device (ultrasonicgenerator) are combined.

FIG. 19 is a schematic cross-sectional view that shows one embodiment ofa manufacturing device for conductive fine particles of the presentinvention 11.

FIG. 20 is a schematic cross-sectional view that shows a conventionalmanufacturing device for conductive fine particles.

FIG. 21 is a time chart showing operation conditions of Example 20.

FIG. 22 is a time chart showing operation conditions of Example 21.

FIG. 23 is a time chart showing operation conditions of ComparativeExample 10.

FIG. 24 is a time chart showing operation conditions of ComparativeExample 11.

FIG. 25 is a graph that shows a relationship between the thickness of anelectroless nickel plating film and the specific gravity of fineparticles.

FIG. 26 is a time chart showing one embodiment of operation conditionsof the present invention 14.

FIG. 27 is a time chart showing operation conditions of Example 27 andExample 31.

FIG. 28 is a time chart showing operation conditions of Example 28.

FIG. 29 is a time chart showing operation conditions of Example 29.

FIG. 30 is a time chart showing operation conditions of Example 30.

FIG. 31 is a time chart showing operation conditions of Example 31.

FIG. 32 is a time chart showing operation conditions of Example 32.

FIG. 33 is a time chart showing operation conditions of Example 33.

FIG. 34 is a time chart showing operation conditions of ComparativeExample 14.

FIG. 35 is a time chart showing operation conditions of ComparativeExample 15.

FIG. 36 is a time chart showing operation conditions of ComparativeExample 16.

FIG. 37 is a time chart showing operation conditions of ComparativeExample 17.

FIG. 38 is a time chart showing operation conditions of CompativeExample 18.

FIG. 39 is a cross-sectional view that schematically shows laminatedconductive fine particles of the present invention 17.

FIG. 40 is a cross-sectional view that schematically shows doublelaminated conductive fine particles of the present invention 17.

FIG. 41 is a cross-sectional view that schematically shows an electroniccircuit element of the present invention on which laminated conductivefine particles are stacked.

FIG. 42 is a cross-sectional view that schematically shows an electroniccircuit substrate of the present invention on which laminated conductivefine particles are stacked.

FIG. 43 is a cross-sectional view that schematically shows an electroniccircuit element of the present invention on which double laminatedconductive fine particles are stacked.

FIG. 44 is a cross-sectional view that schematically shows an electroniccircuit substrate of the present invention on which double laminatedconductive fine particles are stacked.

FIG. 45 is a cross-sectional view that schematically shows an electroniccircuit part of the present invention.

FIG. 46 is an explanatory drawing that schematically shows a flip chipbonding method using solder bumps.

FIG. 47 is an explanatory drawing that schematically shows a flip chipbonding method using solder coat balls each having a highly rigid core.

FIG. 48 is an explanatory drawing that schematically shows a flip chipbonding method using a bump transfer system.

FIG. 49 is an explanatory drawing that schematically shows a flip chipbonding method using bumps formed by conductive resin.

FIG. 50 is an explanatory drawing that schematically shows a flip chipbonding method using an anisotropic conductive adhesive.

FIG. 51 is an explanatory drawing that schematically shows anelectroplating device used in the present invention, wherein respectivereference numerals are used in the drawing:

EXPLANATION OF REFERENCE NUMERALS

-   1 hollow cover-   2 electrode-   2 a anode-   3 driving shaft-   4 container-   5 level sensor-   6 supply tube-   7 drain tube-   8 opening-   9 contact brush-   10 bottom plate-   11 contact ring-   12 ring-shaped porous member-   13 treatment chamber-   14 hollow cover sealing lid-   15 packing-   16 anode side contact brush-   17 universal joint-   18 air drawing valve-   19 ring-shaped porous support-   20 sheet-shaped filter-   21 plate-shaped porous member-   22 plate-shaped porous support-   214 container-   215 suspension of plating solution and fine particles-   216 pump-   217 pressure gage-   218 chamber-   219 heat exchanger-   220 plating solution receiving vessel-   221 fine particle drawing tube-   222 ground fine particle supply tube-   223 fine particle circulating pump-   224 plating solution circulating pump-   225 pipeline homomixer-   226 static mixer-   227 ultrasonic generator-   228 pure water-   229 glass container-   230 ground particle transporting pump-   331 plated fine particle drawing pump-   313 plating vessel-   314 partition plate-   315 treatment chamber-   316 filter sheet-   317 porous support-   111 base particle-   122 conductive metal layer-   333 low melting point metal layer-   444 conductive fine particles-   555 electrode section-   666 electronic circuit element-   777 electrode section-   888 electronic circuit substrate-   999 low melting point metal-   510 under fill

DETAILED DESCRIPTION OF THE INVENTION

Referring to Figures, the following description will discuss embodimentsof the manufacturing device for conductive fine particles of the presentinvention in detail.

FIG. 1 shows one embodiment of a manufacturing device for conductivefine particles of the present invention.

The manufacturing device for conductive fine particles of the presentinvention 1 comprises: a disk-shaped bottom plate 10 secured to theupper end of a perpendicular driving shaft a porous member 12 that isplaced on the outer circumferential upper face of the bottom plate 10and that allows only a plating solution to pass there through; a contactring 11 for conducting electricity placed on the upper face of theporous member; a hollow cover 1 of a trapezoidal cone shape having anopening 8 on its upper center portion, to the upper end of which ahollow cylinder having the same pore diameter as the opening diameter isjoined, with the upper end of the hollow cylinder being bent toward theinner wall side of the hollow cylinder; a rotatable treatment chamber 13formed in a manner so as to sandwich the porous member 12 and thecontact ring 11 between the outer circumferential portion of the hollowcover 1 and the bottom plate 10; a supply tube 6 for supplying theplating solution to the treatment chamber 13 through the opening 8; acontainer 4; for receiving the plating solution scattered from the poresof the porous member 12; a drain tube 7 for draining the platingsolution accumulated in the container 4, and an electrode 2 that isinserted through the opening 8 to contact the plating solution.

The above-mentioned porous member 12 has a ring shape, and is afilter-shaped porous member having communicating bubbles comprisingplastics or ceramics. Those members, which have a pore size allowing aliquid such as a plating solution to pass there through but not allowingfine particles and conductive fine particles obtained to pass therethrough, are adopted.

The plating solution, subjected to a centrifugal force by the rotationof the driving shaft 3, is allowed to pass the porous member 12, andscattered into the plastic container 4, with the result that the liquidlevel of the plating solution inside the treatment chamber 13 drops,therefore, in order to compensate for the reduction, the amount of theliquid is monitored by a level sensor 5 so that the plating solution issupplied to the treatment chamber 13 from the supply tube 6 forsupplying the plating solution through the opening 8 and the liquidlevel inside the treatment chamber 13 is always made to contact anelectrode 2 a. In FIG. 1, reference numeral 2 represents a positiveelectrode that is connected to the anode 2 a. Reference numeral 9 is acontact brush. Here, a power supply used for the electrodes is not shownin the Figure.

In the present invention 1, the plating solution is supplied to thetreatment chamber 13 from the plating solution supply tube 6, and fineparticles having a conductive base layer formed thereon are charged intothe treatment chamber 13 through the opening 8 of the hollow cover 1,and dispersed therein. With respect to the formation of the conductivebase layer, electroless plating is preferably adopted; however, notlimited by this, other known conductivity-applying methods may beadopted. Upon introducing the fine particles into the treatment chamber13, the driving shaft 3 is allowed to rotate. Since the plating solutionpasses through the porous member 12 and goes out of the treatmentchamber 13 while being subjected to the rotation of the driving shaft 3,the plating solution supply tube 6 compensates for the amount of thereduction. Other plating conditions are not particularly distinct fromgeneral plating operations.

In order to form a more uniform plating layer, it is preferable toreverse in its rotation direction or to stop the rotation of the drivingshaft 3 in each predetermined time.

In the manufacturing device for conductive fine particles of the presentinvention 1, the hollow cover 1 has a shape in which, to the upper endof the cover having a trapezoidal cone shape with the opening 8 on itsupper center portion, a hollow cylinder having the same pore diameter asthe opening diameter is joined, with the upper end of the hollowcylinder being bent toward the inner wall side of the hollow cylinder;therefore, even if, by increasing the number of revolutions of thedriving shaft 3 to increase the peripheral velocity of the treatmentchamber 13, the plating solution, subjected to a force in the outercircumferential direction by the effect of a centrifugal force by therotation, forms a vortex having a mortar-like shape and gradually risesalong the inner wall of the cover 1 in the treatment chamber asillustrated in FIG. 3, there is no possibility of overflow. Moreover,even if the peripheral velocity further increases, and the solutionrises to the upper end of the cover, there is no possibility ofscattering of the solution outside the hollow cover 1. Therefore, in themanufacturing device for conductive fine particles of the presentinvention 1, in the case when the fine particles having the conductivebase layer formed thereon have a particle size of not more than 100 μm,the peripheral velocity of the treatment chamber 13 can be increased toa sufficient velocity so as to form a uniform plating layer.

The upper end of the hollow cover 1 may be formed into any shape as longas it prevents the plating solution from overflowing the treatmentchamber; for example, shapes shown in FIGS. 4, 5 and 6 may be adopted.Moreover, as illustrated in FIG. 7, a lid 14 for sealing the hollowcover, attached to the electrode 2, and the hollow cover 1 may seal thetreatment chamber 13 while allowing the treatment chamber 13 and theelectrode 2 to freely rotate. In this case, it does not have toconsidered to control the liquid level by the use of a liquid levelgage.

The manufacturing device for conductive fine particles of the presentinvention 2 has the same construction as that of the manufacturingdevice for conductive fine particles of the present invention 1, exceptthat a hollow cover has a trapezoidal cone shape with an opening on theupper center portion thereof and that a porous member comprises aplate-shaped porous support and a sheet-shaped filter, affixed on innerside face thereof, having a thickness of 10 to 1000 μm with a pore sizeallowing only a plating solution to pass there through.

In the present invention 2, by using such a porous member, it becomespossible to prevent clogging and overflow of particles withoutdecreasing the amount of the liquid passage.

FIG. 8 shows a cross-sectional structure of one embodiment of a porousmember used in the present invention 2. The porous member used in thisembodiment comprises affixing a sheet-shaped filter 20 having athickness of 10 to 1000 μm with a pore size that allows only a platingsolution to pass there through onto the inner side surface of aring-shaped porous support 19. The filter 20 may be affixed onto onlythe inner side surface of the ring-shaped porous support 19, however itis preferable to affixed onto the upper surface and lower surface of thering-shaped porous support 19 in an extended wrapping manner to besandwiched by the contact ring 11 and the base plate 10.

The material of the ring-shaped porous support 19 is not particularlylimited; and for example, polypropylene; polyethylene, ceramics, etc.are used.

The pore size of the ring-shaped porous support 19 is not related to theparticle size of the fine particles to be loaded into the treatmentchamber 13, and it only requires to have a sufficient strength to formthe treatment chamber, and set in the range of 50 to 600 μm, and morepreferably, 70 to 300 μm.

The material of the sheet-shaped filter 20 is not particularly limited;and for example, nylon 66, nonwoven fabric of polyester, Teflon, etc.are used.

The pore size of the sheet-shaped filter 20 is appropriately selectedaccording to the particle size of the fine particles, thus platingobjects. Moreover, a plurality of filters may be overlapped to adjustthe amount of passage.

The manufacturing device for conductive fine particles of the presentinvention 3 has the same construction as that of the manufacturingdevice for conductive fine particles of the present invention 1, exceptthat the porous member comprises a plate-shaped porous support and asheet-shaped filter, affixed on upper face thereof, having a thicknessof 10 to 1000 μm with a pore size allowing only a plating solution topass there through. In other words, the manufacturing device forconductive fine particles of the present invention 3 comprises both ahollow cover with its upper end being bent toward the inner side wallside of the hollow cylinder, which forms a feature of the manufacturingmethod for conductive fine particles of the present invention 1, and thering-shaped porous member comprising the ring-shaped porous support andthe sheet-shaped filter according to the manufacturing device forconductive fine particles of the present invention 2.

The manufacturing device for conductive fine particles of the presentinvention 3 has such a construction that, when the peripheral velocityof the treatment chamber increases, and even when the plating solution,subjected to a force in the outer circumferential direction due to acentrifugal force by the rotation, forms a mortar-like-shaped vortexinside the treatment chamber and rises gradually along the inner wall ofthe cover, overflow and scattering the liquid outside the hollow coverdo not occur, and it is possible to prevent clogging and overflow ofparticles without reducing the amount of liquid passage; therefore, itbecomes possible to form a uniform plating layer efficiently, even inthe case when the fine particles, each having a conductive base layerformed thereon, have a particle size of not more than 100 μm.

FIG. 9 shows one embodiment of a manufacturing device for conductivefine particles of the present invention 4.

The manufacturing device for conductive fine particles of the presentinvention 4 comprises a disk-shaped bottom plate 10 secured to the upperend of a perpendicular driving shaft; a plate-shaped porous member 21that is placed on the upper face of the bottom plate 10 and that allowsonly a plating solution to pass there through; a contact ring 11 forconducting electricity placed on the upper face of the porous member 21;a hollow cover 1 of a trapezoidal cone shape having an opening 8 on itsupper center portion; a rotatable treatment chamber 13 formed in amanner so as to sandwich the porous member 21 and the contact ring 11between the outer circumferential portion of the hollow cover 1 and thebottom plate 10; a supply tube 6 for supplying the plating solution tothe treatment chamber 13 through the opening 8; a container 4 forreceiving the plating solution scattered from the pores of the porousmember 21; a drain tube 7 for draining the plating solution accumulatedin the container 4; and an electrode 2 that is inserted through theopening 8 to contact the plating solution.

The manufacturing device for conductive fine particles of the presentinvention 4 has the same construction as that of the manufacturingdevice for conductive fine particles of the present invention 1, exceptthat the hollow cover of a trapezoidal cone shape having an opening onits upper center portion, and that the porous member has a plate shape.

In the manufacturing device for conductive fine particles comprising aring-shaped porous member, in the case when plating is applied to fineparticles having a particle size of not more than 100 μm, the fineparticles are pressed onto the porous member filtering face due to theflow of liquid from the porous member, with the result that ring-shapedaggregated lumps may be produced. Here, the plate-shaped porous memberhas a wider cross-sectional area through which the plating solutionpasses as compared with the ring-shaped porous member. Accordingly, themanufacturing device for conductive fine particles of the presentinvention 4 makes the passage flow speed through the filtering faceslower, thereby solving the problem of the production of ring-shapedaggregated lumps due to pressed fine particles on the porous memberfiltering face.

The manufacturing device for conductive fine particles of the presentinvention 5 has the same construction as the manufacturing device forconductive fine particles of the present invention 4, except that, tothe upper end of the hollow cover of a trapezoidal cone shape having anopening on its upper center portion, a hollow cylinder having the samepore diameter as the opening diameter is joined, with the upper end ofthe hollow cylinder being bent toward the inner wall side of the hollowcylinder. In other words, the manufacturing device for conductive fineparticles of the present invention 5 comprises the hollow cover with theupper end being bent toward the inner wall side of the hollow cylinderwhich features the manufacturing device for conductive fine particles ofthe present invention 1 and the plate-shaped porous member whichfeatures the manufacturing device for conductive fine particles of thepresent invention 4.

FIG. 10 shows one embodiment of the manufacturing device for conductivefine particles of the present invention 5.

Since the manufacturing device for conductive fine particles of thepresent invention 5 has such a construction that even in the case whenthe peripheral velocity of the treatment chamber increases and theplating solution, subjected to a force in the outer circumferentialdirection due to the effect of a centrifugal force by the rotation,forms a mortar-shaped vortex in the treatment chamber and risesgradually along the inner wall of the cover, overflow and scattering ofthe liquid outside the hollow cover do not occur; moreover, since thepassage flow speed through the filtering face is slower, it becomespossible to solve the problem of the occurrence of ring-shapedaggregated lumps due to the pressed fine particles on the porous memberfiltering face.

The manufacturing device for conductive fine particles of the presentinvention 6 has the same construction as that of the manufacturingdevice for conductive fine particles of the present invention 4 or themanufacturing device for conductive fine particles of the presentinvention 5, except that the porous member comprises a disk-shapedporous support and a sheet-shaped filter, affixed on upper face thereof,having a thickness of 10 to 1000 μm with a pore size allowing only aplating solution to pass there through.

In the present invention 6, the application of this porous member makesit possible to effectively prevent clogging and overflow of particleswithout the need for reducing the amount of liquid passage.

FIG. 11 shows one embodiment of the manufacturing device for conductivefine particles of the present invention 6.

The porous member used in this embodiment comprises a plate-shaped poresupport 22 and a sheet-shaped filter 20, affixed on upper side facethereof, having a thickness of 10 to 1000 μm with a pore size allowingonly a plating solution to pass there through. The plate-shaped poroussupport 22 is the same as the ring-shaped porous support 19 except itsshape.

Moreover, with respect to another embodiment of the manufacturing devicefor conductive fine particles of the present invention 6, as illustratedin FIG. 12, between the ring-shaped porous support 19 placed on theupper face outer circumferential portion of the bottom plate 10 and thecontact ring 11, a sheet-shaped filter 20 may be placed so as to allowthe entire bottom face of the treatment chamber 13 to form a filteringface, thereby forming a structure in which the inside of the treatmentchamber 13 is divided by the sheet-shaped filter 20.

With respect to the materials for a plating layer of conductive fineparticles produced by the manufacturing devices for conductive fineparticles of the present inventions 1, 2, 3, 4, 5 and 6, they are notparticularly limited, but include, for example, gold, silver, copper,platinum, zinc, iron, tin, aluminum, cobalt, indium, nickel, chromium,titanium, antimony, bismuth, germanium, cadmium, silica, and the like.One of these materials may be used, or not less than two kinds of thesemay be used concomitantly.

Those fine particles used in the manufacturing devices for conductivefine particles of the present inventions 1, 2, 3, 4, 5 and 6 may beeither organic resin fine particles or inorganic fine particles.

The above-mentioned fine particles are preferably set to have a particlesize of 0.5 to 5000 μm and a variation coefficient of not more than 50%.

In the present inventions 7, 8 and 9, an electroplating layer is formedon the surface of each of the fine particles by a plating process. Inparticular, it is preferable to form the electroplating layer on thesurface of each of the fine particles by a plating process in which thefine particles are made to collide with the cathode by a centrifugalforce in a plating bath provided with a cathode and an anode.

In the present inventions 7, 8 and 9, a step is required which comprisesapplying at least one kind of force selected from the group consistingof a shearing force, an impact force and cavitation, in order todisperse, pulverize and divide into individual particles, aggregatedlumps of fine particles formed during the plating process.

In the present invention 7, the method for applying at least one kind offorce selected from the group consisting of a shearing force, an impactforce and cavitation is not particularly limited; and examples includemethods using a pulverizing device, such as a static mixer, a homomixer,a homogenizer, a stirrer, a pump, and ultrasonic waves. The cavitation(pressure drop) means a phenomenon in which the pressure of a flowingliquid drops locally, thereby generating bubbles containing vapor andgases.

The above-mentioned plating process is carried out with anelectroplating device.

With respect to the electroplating device, it is not particularlylimited as long as it is generally used; and, for example, asillustrated in FIG. 1, an electroplating device comprising the followingequipment is preferably used: a disk-shaped bottom plate secured to theupper end of a perpendicular driving shaft; a porous member that isplaced on the outer circumferential upper face of the bottom plate andthat allows only a plating solution to pass there through; a contactring for conducting electricity placed on the upper face of the porousmember; a hollow cover of a trapezoidal cone shape having an opening onits upper center portion, to the upper end of which a hollow cylinderhaving the same pore diameter as the opening diameter is joined, withthe upper end of the hollow cylinder being bent toward the inner wallside of the hollow cylinder; a rotatable treatment chamber formed in amanner so as to sandwich the porous member and the contact ring betweenthe outer circumferential portion of the hollow cover and the bottomplate; a supply tube for supplying the plating solution to the treatmentchamber through the opening; a container for receiving plating solutionscattered from the pores of the porous member; a drain tube for drainingthe plating solution accumulated in the container; and an electrodeinserted through the opening to contact the plating solution.

In the present inventions 7, 8 and 9, the above-mentioned electroplatingdevice and the above-mentioned pulverizing device are concomitantly usedso that the fine particle aggregated lumps produced during the platingprocess can be dispersed, pulverized and divided into an individualparticle, thereby making it possible to uniformly form an electroplatinglayer on the surface of each of the fine particles.

With respect to the method for combining the above-mentionedelectroplating device and the pulverizing device, for example, aftercompletion of the plating process by the above-mentioned electroplatingdevice, the resulting product may be divided into an individual particleby using the pulverizing device; however, in this case, scratches andscrape marks remain on the surface of the plated fine particles, failingto form a uniform plating layer. Accordingly, it is preferable tocontinuously carry out the dividing process into individual particles bythe pulverizing device while forming the plating layer in theelectroplating device. Moreover, the fine particles may be circulateduntil an objective film thickness has been achieved, or theelectroplating device and the pulverizing device may be aligned inseries so as to carry out a single-pass plating process.

In the present inventions 7, 8 and 9, the electroplating layer of fineparticles is not particularly limited, but includes, for example, atleast one kind of metal selected from the group consisting of thefollowing metals is preferably used: gold, silver, copper, platinum,zinc, iron, lead, tin, aluminum, cobalt, indium, nickel, chromium,titanium, antimony, bismuth, germanium, cadmium, silica, and the like.

Those fine particles used in the manufacturing devices for conductivefine particles of the present inventions 7, 8 and 9 may be eitherorganic resin fine particles or inorganic fine particles.

The above-mentioned fine particles are preferably set to have a particlesize of 0.5 to 5000 μm and a variation coefficient of not more than 50%.

The manufacturing method for conductive fine particles of the presentinventions 7, 8 and 9 provide the following effects:

{circle around (1)} Because of comprising a step of applying at leastone kind of force selected from the group consisting of a shearingforce, an impact force and cavitation, it is possible to obtainconductive fine particles divided into an individual particle which havea plating layer of a uniform thickness, even when fine particles have aparticle size of approximately not more than 100 μm.

{circle around (2)} The electroplating device and the pulverizing deviceare aligned in series so that a plating layer is formed in theelectroplating device while fine particles are continuously beingdivided into an individual particle in the pulverizing device;therefore, it is possible to obtain conductive fine particles with aplating layer having a uniform thickness without scrap marks andscatches on the surface of the plated fine particles.

Referring to Figures, the following description will discuss oneembodiment of a manufacturing device for conductive fine particles ofthe present invention 10.

FIG. 1 shows one embodiment of an electroplating device used in themanufacturing device for conductive fine particles of the presentinvention 10. FIG. 15 shows a flow diagram of one embodiment of acirculating system in which the electroplating device and thepulverizing device are combined in the manufacturing device forconductive fine particles of the present invention 10.

As illustrated in FIG. 1, the electroplating device used in themanufacturing device for conductive fine particles of the presentinvention 10 comprises a disk-shaped bottom plate 10 secured to theupper end of a perpendicular driving shaft 3; a porous member 12 that isplaced on the outer circumferential upper face of the bottom plate 10and that allows only a treatment liquid to pass there through and; acontact ring 11 for conducting electricity placed on the upper face ofthe porous member; a hollow cover 1 of a trapezoidal cone shape havingan opening 8 on its upper center portion, to the upper end of which ahollow cylinder having the same pore diameter as the opening diameter isjoined, with the upper end of the hollow cylinder being bent toward theinner wall side of the hollow cylinder; a rotatable treatment chamber 13formed in a manner so as to sandwich the porous member 12 and thecontact ring 11 between the outer circumferential portion of the hollowcover 1 and the bottom plate 10; a supply tube 6 for supplying thetreatment liquid to the treatment chamber 13 through the opening 8; acontainer 4 for receiving the treatment liquid scattered from the poresof the porous member 12; a drain tube 7 for draining the treatmentliquid accumulated in the container 4; and an electrode 2 insertedthrough the opening 8 to contact the plating solution.

The above-mentioned porous member 12 is a filter-shaped porous membercomprising communicating bubbles formed with plastics or ceramics. Thosemembers, which have a pore size that allows a treatment liquid such as aplating solution to pass there through but does not allow fine particlesand conductive fine particles to do, are adopted.

The treatment liquid, subjected to a centrifugal force by the rotationof the driving shaft 3, is allowed to pass the porous member 12, andscattered into the plastic container 4, with the result that the liquidlevel of the theatment solution inside the treatment chamber 13 drops;therefore, in order to compensate for the reduction, the amount of theliquid is monitored by a level sensor 5 so that the treatment liquid issupplied to the treatment chamber 13 from the supply tube 6 forsupplying the treatment liquid through the opening 8 and the liquidlevel inside the treatment chamber 13 is always made to contact anelectrode 2 a. In FIG. 1, reference numeral 2 represents a positiveelectrode that is connected to the anode 2 a. Reference numeral 9 is acontact brush. A power supply used for the electrodes is not shown inthe Figure.

In the present invention 10, the plating solution is supplied to thetreatment chamber 13 from the plating solution supply tube 6, and fineparticles, each having a conductive base layer formed thereon, arecharged into the treatment chamber 13 through the opening 8 of thehollow cover 1, and dispersed therein. With respect to the formation ofthe conductive base layer, electroless plating is preferably adopted;however, not limited, and other known conductivity-applying methods maybe adopted. Upon introducing the fine particles into the treatmentchamber 13, the driving shaft 3 is allowed to rotate. Since the platingsolution passes through the porous member 12 and goes out of thetreatment chamber 13 with being subject to the rotation of the drivingshaft 3, the plating solution supply tube 6 compensates for the amountof the reduction. Other plating conditions are not particularly distinctfrom general plating operations.

In order to form a more uniform plating layer, it is preferable toreverse in its rotation direction or to stop the rotation of the drivingshaft 3 in each predetermined time.

In the present invention 10, the fine particles, each having aconductive base layer formed thereon, are placed in the treatmentchamber 13 while being immersed in a plating solution, and power isapplied across the respective electrodes of the contact ring 11(cathode) and the anode 2 a while the driving shaft 3 being rotated. Thefine particles are pressed against the contact ring 11 by the effect ofa centrifugal force so that a plating layer is formed on each of thefine particles facing the anode 2 a. When the driving shaft 3 isstopped, the fine particles are dragged by gravity and the flow of theplating solution due to inertia, made to drop on the flat surface of thecentral portion of the bottom plate, and mixed. When the driving shaft 3starts to rotate reversely next time, they are pressed against thecontact ring 11 by the effect of a centrifugal force in a differentattitude while being mixed so that a plating layer is formed on each ofother fine particles facing the anode 2 a.

As described above, a plating process is carried out by repeating therotation and stoppage of the driving shaft 3; and, as illustrated inFIG. 15, during this plating process, the fine particles inside thetreatment chamber 13 are continuously taken out together with theplating solution, and transported to the pulverizing device. The fineparticles, transported to the pulverizing device, are subjected to atleast one kind of force selected from the group consisting of shearingforce, impact force and cavitation (pressure drop), and divided into anindividual particle, and these are again returned to the treatmentchamber of the electroplating device.

By repeating these processes, it becomes possible to prevent aggregationof the fine particles, and consequently to provide conductive fineparticles, each having a uniform electroplating layer formed thereon.

FIG. 19 shows one embodiment of a manufacturing device for conductivefine particles of the present invention 11.

The manufacturing device for conductive fine particles of the presentinvention 11 comprises a disk-shaped bottom plate 10 secured to theupper end of a perpendicular driving shaft 3; a porous member 12 that isplaced on the outer circumferential upper face of the bottom plate 10and that allows only a plating solution to pass there through; a contactring 11 for conducting electricity that is placed on the upper face ofthe porous member 12; a hollow cover 1 having an opening 8 on its uppercenter portion; a rotatable plating vessel 313 formed in a manner so asto sandwich the porous member 12 and the contact ring 11 between theouter circumferential portion of the hollow cover 1 and the bottom plate10; a treatment chamber 315, placed inside the plating vessel 313, thatis formed by a partition plate 314 passing only a plating solution, andincludes the inside face of the contact ring 11; a supply tube 6 forsupplying the plating solution to the plating vessel 313 through theopening 8; a container 4 for receiving the plating solution scatteredfrom the pores of the porous member 12; a drain tube 7 for draining theplating solution accumulated in the container 4; and an electrode 2inserted through the opening 8 to contact the plating solution.

The plating solution, subjected to a centrifugal force by the rotationof the driving shaft 3, is allowed to pass the porous member 12, andscattered into the container 4. Consequently, the liquid level of theplating solution in the plating vessel 313 drops; therefore, in order tocompensate for the reduction, the amount of the liquid is monitored by alevel sensor 5 so that the plating solution is supplied to the platingvessel 313 from the supply tube 6 for supplying the plating solutionthrough the opening 8 and the liquid level in the plating vessel 313 isalways made to contact an electrode 2 a. In FIG. 19, reference numeral 2represents a positive electrode connected to the anode 2 a. Referencenumeral 9 is a contact brush. A power supply used for the electrodes isnot shown in the Figure.

In the present invention 11, fine particles are charged into thetreatment chamber 315, and a plating solution is supplied into theplating vessel 313 through the supply tube 6. Since the plating solutionpasses through the porous member 12 and goes out of the plating vessel313 subjected to the rotation of the driving shaft 3, the platingsolution supply tube 6 compensates for the amount of the reduction.Other plating conditions are not particularly distinct from generalplating operations.

In order to form a more uniform plating layer, it is preferable toreverse in its rotation direction or to stop the rotation of the drivingshaft 3 in each predetermined time.

Power is applied while the fine particles are being pressed onto thecontact ring 11 by the effect of a centrifugal force due to the rotationof the plating vessel 313, and plating is carried out. Simultaneouslywith the power cut-off, the rotation is slowed and stopped, with theresult that the fine particles are dragged by gravity and the flow ofthe plating solution due to inertia, and shifted to the central portionof the bottom plate 10; however, since they are shielded by thetreatment chamber 15 formed with the partition plate 314 allowing onlythe treatment liquid to pass there through, they collide with the innerwall of the treatment chamber 315, and are mixed violently. Next, whenthe plating vessel 13 rotates, the fine particles are pressed againstthe contact ring 11 in a different attitude while being mixed, andsubjected to plating. By repeating this cycle, all the fine particlescontained in the treatment chamber 315 are allowed to have a platinglayer of a uniform thickness.

As described above, in the manufacturing device for conductive fineparticles of the present invention, fine particles are allowed to shiftonly ones inside of the treatment chamber 315 formed inside the platingvessel 313. For this reason, it is possible to shorten the distance ofshift of the fine particles, and consequently to shorten the timerequired for the fine particles until pressed against the contact ring11; therefore, the efficiency of plating is improved. Moreover, uponstoppage of the rotation of the plating vessel 313, the fine particlesare made to collide with the inner wall of the treatment chamber 315,and mixed, resulting in a superior stirring effect.

The size of the treatment chamber 315 is appropriately set by takinginto account the particle size of the fine particles, the kind ofplating metal, etc. It is preferable to set the distance (particle shiftdistance) from the inner side face of the contact ring 11 to the innerside face of the opposing partition plate 314, shown in A of FIG. 19, tobe greater than the thickness of the fine particle layer in the statewhere the fine particles are pressed against the contact ring 11, and itis also preferable to set this distance smaller than the distance fromthe inner side face of the contact ring 11 to the outer circumferentialface of the electrode 2 a inserted into the center of the plating vessel313, as an anode shown in B in FIG. 19 (particle shift distance in thecase of no formation of the treatment chamber 315 inside the platingvessel 13).

With respect to the partition plate 314 forming the treatment chamber315, its shape and material are not particularly limited as long as itallows only the plating solution to pass through. However, it ispreferable to use a plate having a construction wherein a filter sheethas a pore size allowing only the treatment liquid to pass but notallowing fine particles to do is affixed to the inner side face of aresin plate comprising a number of pores. The shape and the size of thepores are only required to set so as to allow smooth passage for theplating solution, regardless of the particle size of fine particles tobe loaded into the treatment chamber 315. Moreover, the thickness of theresin plate also is not particularly limited as long as it hassufficient strength for forming the treatment chamber 315.

The fine particles used in the manufacturing device for conductive fineparticles of the present invention 11 may be either organic resin fineparticles or inorganic fine particles. The fine particles are preferablyones comprising a conductive base layer. With respect to the formationmethod of the conductive base layer, the electroless plating method ispreferably used; however, not limited to this method, other knownconductivity-applying methods may be adopted.

The above-mentioned organic resin fine particles may be fine particlescomprising a linear polymer, fine particles comprising a networkpolymer, fine particles comprising a thermosetting resin, or fineparticles comprising an elastic member.

With respect to the linear polymer, it is not particularly limited, butinclude for examples, nylon, polyethylene, polypropylene, methylpentenepolymer, polystyrene, polymethylmethacrylate, polyvinyl chloride,polyvinyl fluoride, polytetrafluoroethylene, polyethylene terephthalate,polybutyleneterephthalate, polysulfone, polycarbonate,polyacrylonitrile, polyacetal, polyamide, and the like.

With respect to the network polymer, it is not particularly limited, butincludes for example, mono-polymers of crosslinkable monomer, such asdivinylbenzene, hexatoluene, divinylether, divinylsulfone,diallylcarbinol, alkylenediacrylate, oligo orpoly(alkyleneglycol)diacrylate, oligo orpoly(alkyleneglycol)dimethacrylate, alkylenetriacrylate, alkylenetrimethacylate, alkylenetetraacrylate, alkylenetetramethacrylate,alkylenebisacrylamide, and alkylenebismethacylamide, or copolymers ofthese crosslinkable monomers and other polymerizable monomers. Amongthese, divinylbenzene, hexatoluene, divinylether, divinylsulfone,alkylenetriacrylate, alkylenetetraacrylate, etc. are more preferablyused.

With respect to the thermosetting resin, it is not particularly limited,but includes for example, phenol-formaldehyde resins,melamine-formaldehyde resins, benzoguanamine-formaldehyde resins,urea-formaldehyde resins, epoxy resins, etc.

With respect to the elastic member, it is not particularly limited, butincludes for example, natural rubber, synthetic rubber, etc.

With respect to the material for the inorganic fine particles, it is notparticularly limited, but includes for example, silica, titanium oxide,iron oxide, cobalt oxide, zinc oxide, nickel oxide, manganese oxide,aluminum oxide, etc.

The particle size of the fine particles is preferably set in the rangeof 0.5 to 5000 μm, more preferably 0.5 to 2500 μm, and most preferably 1to 1000 μm.

The variation coefficient of the fine particles is preferably set to notmore than 50%, more preferably, not more than 35%, most preferably, notmore than 20%, and by far the most preferably, not more than 10%. Here,the variation coefficient means a value representing the standarddeviation by the use of percentage based upon the average value; this isrepresented by the following formula:variation coefficient=(standard deviation of particle sizes/averagevalue of particle sizes)×100(%)

With respect to the plating metal used in the manufacturing device forconductive fine particles of the present invention 11, it is notparticularly limited, but includes for example, gold, silver, copper,platinum, zinc, iron, tin, aluminum, cobalt, indium, nickel, chromium,titanium, antimony, bismuth, germanium, cadmium, silica, etc. One ofthese materials may be used, or not less than two kinds of these may beused concomitantly.

In the manufacturing device for conductive fine particles of the presentinvention 11, in the case of not more than 50 μm of the average size ofthe fine particles, or in the case when the plating metal tends toaggregation, like solder, plating may be carried out in a state wheredummy chips are mixed with the fine particles.

In the manufacturing device for conductive fine particles of the presentinvention 12, a plating layer is formed on the surface of each of thefine particles by using a plating process.

In the present invention, the above-mentioned plating process is carriedout by using a manufacturing device for conductive fine particles whichcomprises; a rotatable treatment chamber that has a cathode on its sideface and a filter section allowing a plating solution to pass therethrough and to drain it; and an anode placed in the above-mentionedtreatment chamber in a manner so as not to contact the cathode.

The above-mentioned plating process is carried out by repeating therotation and stoppage of the treatment chamber, and comprises a powerapplication process and a stirring process.

The above-mentioned power application process is a process for forming aplating layer on the surface of each of the fine particles by applyingpower in a state where the treatment chamber is being rotated at aconstant speed. The fine particles, loaded into the treatment chamber,are pressed onto the cathode located on the side face of the treatmentchamber by the effect of a centrifugal force due to the rotation of thetreatment chamber. By applying power in this state, a plating layer isformed on the surface of each of the fine particles. Thereafter, whenthe rotation of the treatment chamber and the power application arestopped at the same time, that is, upon completion of the powerapplication process, the fine particles are dragged by gravity and theflow of the plating solution due to inertia is made to drop on thebottom plate of the treatment chamber and mixed.

When, upon completion of the power application process or the stirringprocess described later, the treatment chamber is again rotated and theabove-mentioned power application process is started, the fine particlesare pressed against the cathode in an attitude different from that atthe time of the previous power application process while being mixed. Byapplying power in this state, a plating layer is further formed on thesurface of each of the fine particles, thereby making it possible toform a plating layer having a uniform thickness on each of all the fineparticles contained in the treatment chamber.

The above-mentioned stirring process is a process which comprisesstirring fine particles by rotating only the treatment chamber. Duringthis stirring process, no power application is made.

The number of revolutions of the treatment chamber in theabove-mentioned stirring process is appropriately selected according tothe degree of aggregation of the fine particles, and it may be the sameas the number of revolutions in the power application process, or may bedifferent therefrom. Moreover, the rotation direction of the treatmentchamber in the above-mentioned stirring process may be set either in theforward or reverse direction; however, in order to improve the stirringeffect, it is preferable to set it in the direction reversed to therotation direction in the preceding process of the current stirringprocess.

The operation pattern of the stirring process may be the same as theoperation pattern of the power application process, or may be differenttherefrom; however, in order to improve the efficiency and the stirringeffect, it is preferably set as short as possible.

The above-mentioned stirring process improves the stirring effect of theplating process as a whole; as a result, it becomes possible to extendthe power application time. Moreover, even in the case when the currentdensity is increased higher than that conventionally used, since theresulting aggregated lumps can be pulverized, it is possible to form auniform plating layer with high efficiency.

It is preferable to carry out the stirring process after the powerapplication process, and the stirring process may be carried out aftercarrying out the power application process a plurality of times.Moreover, in the case when the fine particles tend to aggregation, theabove-mentioned stirring process may be carried out a plurality of timesafter the power application process.

The fine particles used in the manufacturing device for conductive fineparticles of the present invention 12 may be either organic resin fineparticles or inorganic fine particles. The fine particles are preferablyone comprising a conductive base layer thereon. With respect to theformation method of the conductive base layer, the electroless platingmethod is preferably used. However, not limited to this method, otherknown conductivity-applying methods may be adopted.

The above-mentioned organic resin fine particles may be fine particlescomprising a linear polymer, fine particles comprising a networkpolymer, fine particles comprising a thermosetting resin, or fineparticles comprising an elastic member.

With respect to the linear polymer constituting the above-mentioned fineparticles comprising a linear polymer, there can be mentioned, nylon,polyethylene, polypropylene, methylpentene polymer, polystyrene,polymethylmethacrylate, polyvinyl chloride, polyvinylfluoride,polytetrafluoroethylene, polyethylene, terephthalate,polybutyleneterephthalate, polysulfone, polycarbonate,polyacrylonitrile, polyacetal, polyamide, etc.

With respect to the network polymer constituting the above-mentionedfine particles comprising a network polymer, there can be mentioned,monopolymers of crosslinkable monomer, such as divinylbenzene,hexatoluene, divinylether, divinylsulfone, diallylcarbinol,alkylenediacrylate, oligo or poly(alkyleneglycol)diacrylate, oligo orpoly(alkyleneglycol)dimethacrylate, alkylenetriacrylate, alkylenetrimethacylate, alkylenetetraacrylate, alkylenetetramethacrylate,alkylenebisacrylamide, and alkylenebismethacylamide, or copolymers ofthese crosslinkable monomers and other polymerizable monomers. Amongthese, divinylbenzene, hexatoluene, divinylether, divinylsulfone,alkylenetriacrylate, alkylenetetraacrylate, etc.

With respect to the thermosetting resin constituting the above-mentionedfine particles comprising a thermosetting resin, there can be mentioned,phenol-formaldehyde resins, melamine-formaldehyde resins,benzoguanamine-formaldehyde resins, urea-formaldehyde resins, epoxyresins, etc.

With respect to the elastic member, constituting the above-mentionedfine particles of an elastic member, for example, natural rubber,synthetic rubber, etc. are used.

With respect to the material for the inorganic fine particles, it is notparticularly limited; and examples thereof include silica, titaniumoxide, iron oxide, cobalt oxide, zinc oxide, nickel oxide, manganeseoxide, aluminum oxide, etc.

The particle size of the fine particles is preferably set in the rangeof 0.5 to 5000 μm, more preferably 0.5 to 2500 μm, and much morepreferably 1 to 1000 μm. Moreover, the variation coefficient of the fineparticles is preferably set to not more than 50%, more preferably notmore than 35%, much more preferably not more than 20%, and the mostpreferably, not more than 10%. Here, the variation coefficient means avalue which represents the standard deviation by the use of percentagebased upon the average value; this is represented by the followingformula:variation coefficient=(standard deviation of particle sizes/averagevalue of particle sizes)×100(%)

With respect to the plating metal forming the above plating layer usedin the manufacturing device for conductive fine particles of the presentinvention, it is not particularly limited, but includes for examples,gold, silver, copper, platinum, zinc, iron, lead, tin, aluminum, cobalt,indium, nickel, chromium, titanium, antimony, bismuth, germanium,cadmium, silica, etc. These materials may be used singly, or not lessthan two kinds of these may be used concomitantly.

Referring to Figures, the following description will discuss oneembodiment of a manufacturing method of conductive fine particles of thepresent invention 12.

FIG. 11 shows one example of a manufacturing device for conductive fineparticles that is preferably used in the manufacturing method forconductive fine particles of the present invention.

The manufacturing device for conductive fine particles, shown in FIG.11, comprises a disk-shaped bottom plate 10 secured to the upper end ofa perpendicular driving shaft 3; a porous member 21 that is placed onthe outer circumferential upper face of the bottom plate 10 and thatallows only a plating solution to pass there through; a contact ring 11for conducting electricity placed on the upper face of the porous member21; a hollow cover 1 having an opening 8 on its upper center portion; arotatable treatment chamber 13 formed in a manner so as to sandwich theporous member 21 and the contact ring 11 between the outercircumferential portion of the hollow cover 1 and the bottom plate 10; asupply tube 6 for supplying the plating solution to the treatmentchamber 13 through the opening 8; a container 4 for receiving theplating solution scattered from the pores of the porous member 21; adrain tube 7 for draining the plating solution accumulated in thecontainer 4; and an electrode 2 inserted through the opening 8 tocontact the plating solution. Here, in the manufacturing device forconductive fine particles having the above-mentioned construction, thecontact ring 11 forms a cathode, the porous member 21 forms a filtersection, and the electrode 2 forms an anode.

The plating solution, subjected to a centrifugal force due to therotation of the driving shaft 3, is allowed to pass the porous member21, and scattered into the plastic container 4, with the result that theliquid level of the plating solution inside the treatment chamber 13drops; therefore, in order to compensate for the reduction, the amountof the liquid is monitored by a level sensor 5 so that the platingsolution is supplied to the treatment chamber 13 from the supply tube 6for supplying the plating solution through the opening 8 and the liquidlevel inside the treatment chamber 13 is always made to contact with anelectrode 2 a. In FIG. 1, reference numeral 2 represents a positiveelectrode connected to the anode 2 a. Reference numeral 9 is a contactbrush. Here, a power supply used for the electrodes is not shown in theFigure.

In the present embodiment, the plating solution is supplied to thetreatment chamber 13 from the plating solution supply tube 6, and fineparticles, each having a conductive base layer formed thereon, arecharged into the treatment chamber 13 through the opening 8 of thehollow cover 1, and dispersed therein. Since the plating solution passesthrough the porous member 21 and goes out of the treatment chamber 13subjected to the rotation of the driving shaft 3, the plating solutionsupply tube 6 compensates for the amount of the reduction. Other platingconditions are not particularly distinct from general platingoperations.

The above-mentioned porous member 21 is a filter-shaped porous memberhaving communicating bubbles formed by plastics or ceramics, and thosehaving a pore size to pass only the plating solution such as a platingsolution, but not to pass fine particles and conductive fine particlesare adopted; and it is preferably one having a construction in which afilter sheet 20 having a pore size to allow only a plating solution topass there through is placed on the upper face of the plate-shapedporous support 22.

In order to form a more uniform plating layer, it is preferable toreverse in its rotation direction or to stop the rotation of the drivingshaft 3 in each predetermined time. The number of revolutions and theoperation pattern may be the same in both of the forward rotation timeand the reverse rotation time, or may be different in these cases.

In the manufacturing method for conductive fine particles of the presentinvention 13, an electroplating layer is formed on the surface of eachof fine particles by a plating process.

In the present invention 13, the above-mentioned plating process iscarried out by using a manufacturing device for conductive fineparticles which comprises; a rotatable treatment chamber that has acathode on its side face and a filter section allowing a platingsolution to pass there through and to drain it; and an anode placed inthe treatment chamber in a manner so as not to contact the cathode.

Fine particles, loaded into the treatment chamber, are pressed onto thecathode located on the side face of the treatment chamber by the effectof a centrifugal force due to the rotation of the treatment chamber. Byapplying power in this state, an electroplating layer is formed on thesurface of each of the fine particles. Thereafter, when the rotation ofthe treatment chamber and the power application are stopped at the sametime, the fine particles are dragged by gravity and the flow of theplating solution due to inertia, made to drop on the bottom plate, ofthe treatment chamber and mixed. When the treatment chamber is furtherrotated, the fine particles are pressed against the cathode in adifferent attitude while being mixed. By applying power in this state,an electroplating layer is further formed on the surface of each of thefine particles. By repeating the rotation and stoppage of the treatmentchamber, it becomes possible to form an electroplating layer having auniform thickness on all the fine particles contained in the treatmentchamber.

With respect to the fine particles used in the present invention 13,they are not particularly limited, but include for example, metal fineparticles, organic resin fine particles, and inorganic fine particles.In the case of the application of the organic resin fine particles orthe inorganic particles, those fine particles comprising a conductivebase layer on the surface thereof are preferably used. With respect tothe formation method of the conductive base layer, the electrolessplating method is preferably used. However, it is not limited to thismethod, other known conductivity-applying methods may be adopted.

With respect to the metal fine particles, they are not particularlylimited, but include for example, iron, copper, silver, gold, tin, lead,platinum, nickel, titanium, cobalt, chromium, aluminum, zinc, tungsten,etc., and alloys thereof.

The above-mentioned organic resin fine particles may include fineparticles comprising a linear polymer, fine particles comprising anetwork polymer, fine particles comprising a thermosetting resin, andfine particles comprising an elastic member.

With respect to the linear polymer constituting the above-mentioned fineparticles comprising a linear polymer, there can be mentioned, nylon,polyethylene, polypropylene, methylpentene polymer, polystyrene,polymethylmethacrylate, polyvinyl chloride, polyvinylfluoride,polytetrafluoroethylene, polyethylene-terephthalate,polybutyleneterephthalate, polysulfone, polycarbonate,polyacrylonitrile, polyacetal, polyamide, etc.

With respect to the network polymer constituting the above-mentionedfine particles comprising a network polymer, there can be mentioned,mono-polymers of crosslinkable monomer, such as divinylbenzene,hexatoluene, divinylether, divinylsulfone, diallylcarbinol,alkylenediacrylate, oligo or poly(alkyleneglycol)diacrylate, oligo orpoly(alkyleneglycol)dimethacrylate, alkylenetriacrylate,alkylenetrimethacylate, alkylenetetraacrylate,alkylenetetramethacrylate, alkylenebisacrylamide, andalkylenebismethacylamide, or copolymers, etc. obtained by copolymerizingthese crosslinkable monomers and other polymerizable monomers. Amongthese, divinylbenzene, hexatoluene, divinylether, divinylsulfone,alkylenetriacrylate, alkylenetetraacrylate, etc. are more preferablyused.

With respect to the thermosetting resin constituting the above-mentionedfine particles comprising a thermosetting resin, there can be mentionedphenol-formaldehyde resins, melamine-formaldehyde resins,benzoguanamine-formaldehyde resins, urea-formaldehyde resins, epoxyresins, etc.

With respect to the elastic member constituting the above-mentioned fineparticles comprising an elastic member, there can be mentioned, naturalrubber, synthetic rubber, etc.

With respect to the material for the inorganic fine particles, it is notparticularly limited, but includes for example, silica, titanium oxide,iron oxide, cobalt oxide, zinc oxide, nickel oxide, manganese oxide,aluminum oxide, etc.

The particle size of the fine particles is preferably set in the rangeof 0.5 to 5000 μm, more preferably 0.5 to 2500 μm, and much morepreferably 1 to 1000 μm. The variation coefficient of the fine particlesis preferably set to not more than 50%, more preferably not more than35%, much more preferably not more than 20%, and the most preferably notmore than 10%. Here, the variation coefficient means a valuerepresenting the standard deviation by the use of percentage based uponthe average value; this is represented by the following formula:variation coefficient=(standard deviation of particle sizes/averagevalue of particle sizes)×100(%)

In the present invention 13, the difference in the specific gravitybetween the fine particles and the plating solution is set in the rangeof 0.04 to 22.00. When this is less than 0.04, it takes a long time forthe fine particles to come into contact with the cathode, and powerapplication is started before all the fine particles have been pressedon the cathode, with the result that bipolar phenomenon occurs.Moreover, when the number of revolutions of the treatment chamber isincreased in order to increase the shifting speed of the fine particles,the plating solution, which is subjected to a force in the outercircumferential direction due to the effect of a centrifugal force,forms a vortex in a mortar-like shape within the treatment chamber, withthe result that the electrode placed in the center of the treatmentchamber is exposed, resulting in failure to apply electric current.

When the shifting time for the fine particles to reach the cathode takeslong time, the ratio of the power application time in one cycle gets tobe smaller, causing not only degradation in the efficiency, but also anextreme reduction in the amount of power application due to theformation of the vortex in a mortar-like shape by the liquid faceresulting from the long rotation time of the treatment chamber.

Here, the specific gravity of generally known solid substances isapproximately in the range of 0.5 to 23, and in the manufacturing methodof the present invention, the greater the difference in the specificgravity between the fine particles and the plating solution, the moreeffective because the fine particles in the plating solution are allowedto shift more easily.

In other words, the difference in the specific gravity required for aplating process is in the range of 0.04 to 22.00, more preferably 0.04to 11.00, and much more preferably 0.04 to 0.2.

With respect to the method for setting the difference in the specificgravity between the fine particles and the plating solution in theabove-mentioned range, a method for increasing the specific gravity ofthe fine particles and a method for decreasing the specific gravity ofthe plating solution are proposed.

As to the method for increasing the specific gravity of the fineparticles, for example, in the case when the organic resin fineparticles or the inorganic fine particles are used as the fineparticles, a method for increasing the film thickness of the conductivebase layer formed on the surface of each of the fine particles isadopted. More specifically, when the electroless nickel plating(specific gravity: 8.85) is applied to organic resin fine particleshaving a specific gravity of, for example, 1.19, the specific gravity ofthe fine particles increases as the thickness of the plating filmincreases, as shown in a graph in FIG. 1. In this manner, the specificgravity of the fine particles can be controlled desirably by forming theconductive base layer, etc. on the surface of each of the fine particlesby using the electroless plating, etc.

In the method for decreasing the specific gravity of the platingsolution, for example, a method for diluting the plating solution, etc.is proposed. More specifically, for example, in the case when a Wattbath (specific gravity: not less than 1.18) generally used as a platingsolution in a nickel plating process is used, it can be diluted toapproximate 60% with pure water. Here, with respect to additives, it ispreferable to maintain the concentration thereof constant, taking intoconsideration better adhesion of the plating, etc. Moreover, in order toproperly maintain the conductivity of the plating solution, it is alsopreferable to maintain the concentration of nickel chloride constant.Here, a Watt bath having a composition of nickel chloride 35 to 45 g/L,nickel sulfate 140 to 155 g/L and boric acid 30 to 40 g/L forms aspecific gravity in the range of 1.05 to 1.12; and this is preferablyused in the present invention 13.

In the present invention 13, the electroplating layer formed on thesurface of each of the fine particles is not particularly limited, butincludes for example, an electroplating layer, etc. comprising at leastone kind of metal selected from the group consisting of gold, silver,copper, platinum, zinc, iron, lead, tin, aluminum, cobalt, indium,nickel, chromium, titanium, antimony, bismuth, germanium, cadmium andsilica.

Referring to Figures, the following description will discuss oneembodiment of a manufacturing method of conductive fine particles of thepresent invention 13.

FIG. 1 shows one example of a manufacturing device for conductive fineparticles that is preferably used in the manufacturing method forconductive fine particles of the present invention 13.

The manufacturing device for conductive fine particles, shown in FIG. 1comprises a disk-shaped bottom plate 10 secured to the upper end of aperpendicular driving shaft 3; a porous member 12 that is placed on theouter circumferential upper face of the bottom plate 10 and that allowsonly a plating solution to pass there through; a contact ring 11 forconducting electricity placed on the upper face of the porous member 12;a hollow cover 1 having a trapezoidal cone shape with an opening 8 onits upper center portion; a rotatable treatment chamber 13 formed in amanner so as to sandwich the porous member 12 and the contact ring 11between the outer circumferential portion of the hollow cover 1 and thebottom plate 10; a supply tube 6 for supplying the plating solution tothe treatment chamber 13 through the opening 8; a container 4 forreceiving the plating solution scattered from the pores of the porousmember 12; a drain tube 7 for draining the plating solution accumulatedin the container 4, and an electrode 2 inserted through the opening 8 soas to contact the plating solution. Here, in the manufacturing devicefor conductive fine particles having the above-mentioned construction,the contact ring 11 forms a cathode, the porous member 12 forms a filtersection, and the electrode 2 forms an anode.

The plating solution, subjected to a centrifugal force due to therotation of the driving shaft 3, is allowed to pass the porous member12, and scattered into the plastic container 4, with the result that theliquid level of the plating solution in the treatment chamber 13 drops,therefore, in order to compensate for the reduction, the amount of theliquid is monitored by a level sensor 5 so that the plating solution issupplied to the treatment chamber 13 from the supply tube 6 forsupplying the plating solution through the opening 8 and the liquidlevel inside the treatment chamber 13 is always made to contact anelectrode 2 a. In FIG. 2, reference numeral 2 represents a positiveelectrode and is connected to the anode 2 a. Reference numeral 9 is acontact brush. Here, a power supply used for the electrodes is not shownin the Figure.

In the present embodiment, the plating solution is supplied to thetreatment chamber 13 from the plating solution supply tube 6, and fineparticles, each having a conductive base layer formed thereon, arecharged into the treatment chamber 13 through the opening 8 of thehollow cover 1, and dispersed therein. Since the plating solution passesthrough the porous member 12 and goes out of the treatment chamber 13subjected to the rotation of the driving shaft 3, the plating solutionsupply tube 6 compensates for the amount of the reduction. Other platingconditions are not particularly distinct from general platingoperations.

The above-mentioned porous member 12 is a ring-shaped porous member witha filter shape having communicating bubbles formed by plastics orceramics, and those having a pore size to allow only the platingsolution such as a plating solution to pass there through, but not toallow fine particles to do and conductive fine particles are adopted;and a construction may be adopted in which a filter sheet having a poresize that allows only a plating solution to pass there through is placedon the upper face of the plate-shaped porous support.

In order to form a more uniform electroplating layer, it is preferableto reverse in its rotation direction or to stop the rotation of thedriving shaft 3 in each predetermined time. The number of revolutionsand the operation pattern may be the same in both of the forwardrotation time and the reverse rotation time, or may be different inthese cases.

In the manufacturing method for conductive fine particles of the presentinvention 14, an electroplating layer is formed on the surface of eachof fine particles by a plating process.

In the present invention 14, the above-mentioned plating process iscarried out by using a manufacturing device for conductive fineparticles which comprises; a rotatable treatment chamber that has acathode on its side face and a filter section for allowing a platingsolution to pass there through and to drain it; and an anode placed inthe treatment chamber in a manner so as not to contact the cathode.

Fine particles, loaded into the treatment chamber, are pressed onto thecathode on the side face of the treatment chamber by the effect of acentrifugal force due to the rotation of the treatment chamber. Byapplying power in this state, an electroplating layer is formed on thesurface of each of the fine particles. Thereafter, when the rotation ofthe treatment chamber and the power application are stopped at the sametime, the fine particles are dragged by gravity and the flow of theplating solution due to inertia is made to drop on the bottom plate ofthe treatment chamber and mixed. When the treatment chamber is furtherrotated, the fine particles are pressed against the cathode in adifferent attitude while being mixed. By applying power in this state,an electroplating layer is further formed on the surface of each of thefine particles. By repeating the rotation and stoppage of the treatmentchamber, it becomes possible to form an electroplating layer having auniform thickness on all the fine particles contained in the treatmentchamber.

In the present invention 14, the number of revolutions of theabove-mentioned treatment chamber is set so that the centrifugal effectis maintained in the range of 2.0 to 40.0. With the number ofrevolutions of the treatment chamber in this range, it becomes possibleto allow the fine particles to reach the cathode in a shorter time, andconsequently to obtain a sufficient contact force to carry out anelectroplating process, even in the case when there is little differencebetween the true specific gravity of the fine particles and the specificgravity of the plating solution. The centrifugal effect less than 2.0makes the time required for the fine particles to reach the cathodeextremely longer, causing problems such as extreme degradation in theefficiency, an insufficient contact force between the fine particles andthe cathode, and the occurrence of a bipolar phenomenon due to theexistence of fine particles failing to completely reach the cathode;consequently, these problems make it impossible to carry out theelectroplating process. Moreover, in the case of the centrifugal effectexceeding 40.0, although the time required for the fine particles toreach the cathode is greatly shortened, the plating solution, subjectedto a force in the outer circumferential direction due to a centrifugalforce, forms a vortex having a mortar-like shape within the treatmentchamber, with the result that the anode placed in the center of thetreatment chamber is exposed, failing to supply a current flow.Furthermore, in the case when the electroplating layer comprises a metalwhich tends to aggregation and that forms a soft deposition coat film,such as eutectic solder plating, a problem arises in that aggregationoccurs as the coat film grows, when the contact force of the fineparticles to the cathode is too strong. Therefore, the centrifugaleffect is limited to the range of 2.0 to 40.0. The range is morepreferably set to 3 to 30, and much more preferably 7 to 20.

The above-mentioned centrifugal effect is given as the ratio ofmagnitudes between the centrifugal force and the gravity, and found asfollows:

The centrifugal force Fc (N) on the mass point of mass M (kg) incircular motion at a constant velocity is represented by the followingformula:Fc=Mω²r=MV²/r=MN²π²r/900

In the formula, ω represents the rotation angular velocity (rad/sec), rrepresents the rotation radius (m), V represents the peripheral velocity(m/sec), and N represents the rotation speed (rpm).

Therefore the centrifugal effect Z is represented by the followingformula:Z=ω²r/g=V²/gr=N²π²r/900 g

In the formula, g represents gravity acceleration (m/sec²).

From the above-mentioned formula, the centrifugal effect is representedas a function between the rotation speed of the treatment chamber andthe radius of the treatment chamber. The following table shows thenumber of revolutions of the treatment chamber, the centrifugal effectand the peripheral velocity in the case of a treatment chamber having adiameter of 280 mm, as reference. Number of revolutions (rpm) 855 600500 300 250 150 100 Centrifugal 114.5 56.4 39.2 14.1 9.8 3.5 1.6 effectPeripheral 752.1 527.8 439.8 263.9 219.9 131.9 88.0 velocity (m/min.)

In order to form an electroplating layer on the surface of each of allthe fine particles, it is necessary to start power application after alapse of time until all the fine particles have been shifted to thecathode and pressed thereon by the effect of the centrifugal force ofthe rotating treatment chamber. If the power application is startedbefore all the fine particles have been pressed onto the cathode, abipolar phenomenon will occur, causing the electroplating layer or theconductive base layer to melt down and resulting in malplating.

Therefore, in the present invention 14, the power application is startedafter a lapse of 0.5 to 10 seconds from the start of the rotation of thetreatment chamber. In the case of the lapse of less than 0.5 second,since the power application is started before all the fine particleshave been pressed onto the cathode, a bipolar phenomenon occurs, and inthe case of the lapse exceeding 10 seconds, the ratio of the powerapplication time in one cycle gets to be smaller, resulting indegradation in the efficiency; thus, the limitation to theabove-mentioned range is provided. This is more preferably set in therange of 1 to 8 seconds, and much more preferably 1 to 5 seconds. Here,the above-mentioned power application time varies depending on thedifference between the true specific gravity of the fine particles andthe specific gravity of the plating solution and the particle size ofthe fine particles; therefore, this needs to be appropriately set withinthe above-mentioned range depending on factors, such as the material,shape, particle size of the fine particles, the kind of plating metaland the kind of plating bath.

In the present invention 14, the stoppage time of the treatment chamberis set in the range of 0 to 10 seconds. With this range, a sufficientstirring is carried out from the time the fine particles have left thecathode to the time they are again allowed to reach the cathode by thenext rotation; therefore, it is possible to carry out a more uniformplating. If this exceeds 10 seconds, although a uniform plating isobtainable since the fine particles are sufficiently mixed in thetreatment chamber, the ratio of the power application time in one cyclegets to be smaller, resulting in degradation in the efficiency; thus,the above-mentioned limitation to the range is provided. The range ismore preferably set to 0.5 to 5 seconds, and much more preferably 1 to 3seconds. If the stoppage time is too short, the next rotation is startedbefore the fine particles have returned to the center of the bottomplate in the treatment chamber due to the stoppage of the rotation ofthe treatment chamber; this may cause failure to provide sufficientstirring and the subsequent ununiformity in the plating. Here, thestoppage time has variations depending on the difference between thetrue specific gravity of the fine particles and the specific gravity ofthe plating solution, or depending on the pore diameter of fineparticles; therefore, this needs to be appropriately set within theabove-mentioned range depending on factors, such as the material, shape,particle size of the fine particles, the kind of plating metal and thekind of plating bath.

The present invention 15 provides a manufacturing method for conductivefine particles which forms an electroplating layer on the surface ofeach of the fine particles by a plating process, wherein the platingprocess, using a manufacturing device for conductive fine particles thatcomprises; a rotatable treatment chamber that has a cathode on its sideface and a filter section allowing the plating solution to pass therethrough and to drain it; and an anode placed in the treatment chamber ina manner so as not to contact the cathode, comprises steps applyingpower with the fine particles being made contact with the cathode by theeffect of a centrifugal force due to the rotation of the treatmentchamber, so as to form an electroplating layer on the surface of each ofthe fine particles, and then stopping the rotation of the treatmentchamber and the application of power, repeating the rotation andstoppage of the treatment chamber, the number of revolutions of thetreatment chamber is set so that the centrifugal effect in the range of2.0 to 40.0, and the power application is started after a lapse of 3 to10 seconds from the start of the rotation of the treatment chamberbefore the film thickness of the electroplating layer formed on thesurface of each of the fine particles has gotten a predetermined value,and after the film thickness of the electroplating layer formed on thesurface of each of the fine particles has gotten a predetermined value,the power application is started after a lapse of 0.5 to 10 seconds fromthe start of the rotation of the treatment chamber, and said lapse isset shorter than the lapse taken before the film thickness of theelectroplating layer formed on the surface of each of the fine particleshas become a predetermined value.

In the manufacturing method for conductive fine particles of the presentinvention 15, the same manufacturing device for conductive fineparticles as the manufacturing method for conductive fine particles ofthe present invention 14 is used; however, the objective is to prevent abipolar phenomenon that tends to occur at the initial stage of theplating process by delaying the power application start time at theinitial stage of the plating process.

In the present invention 15, the power application is started after alapse of 3 to 10 seconds from the start of the rotation of the treatmentchamber before the film thickness of the electroplating layer formed onthe surface of each of the fine particles has become a predeterminedvalue. In other words, by delaying the power application start time atthe initial stage of the plating process, all the fine particles areallowed to completely reach and contact the cathode so that theoccurrence of a bipolar phenomenon is prevented. Here, in the case whenthe current density is set lower at the initial stage of the platingprocess, it is possible to reduce the possibility of a bipolarphenomenon; therefore, the current density is preferably set in therange of 0.1 to 1.0 A/dm². This is more preferably set in the range of0.2 to 0.5 A/dm².

In the present invention 15, after the film thickness of theelectroplating layer formed on the surface of each of the fine particleshas gotten to be a constant value, the power application is startedafter a lapse of 0.5 to 10 seconds from the start of the rotation of thetreatment chamber, and this lapse is set shorter than the lapse takenbefore the film thickness of the electroplating layer formed on thesurface of each of the fine particles has gotten to be a predeterminedvalue. In other words, when the plating process has progressed and theelectroplating layer has been formed on the surface of each of the fineparticles to a certain extent, the difference in specific gravitybetween the fine particles and the plating solution becomes greater, sothat the fine particles to reach the cathode in a shorter time.Therefor, by shortening the lapse to the power application start time ascompared with the initial stage of the plating process, it becomespossible to improve the efficiency of the plating process. In thisstage, the higher the current density, the higher the efficiency;therefore, the current density is preferably set in the range of 0.5 to5.0 A/dm², and more preferably, 1.0 to 3.0 A/dm².

As described above, by alternating the plating conditions in the courseof the plating process, it becomes possible to prevent the occurrence ofa bipolar phenomenon in the initial stage of the plating process, andconsequently to form an electroplating layer more efficiently. Withrespect to timing for changing the plating conditions, it is preferredthe time when the film thickness of the electroplating layer formed onthe surface of each of the fine particles has reached a predeterminedvalue, with the result that the specific gravity of the fine particlesgets to be greater so that, even if the power application start time,thus, the time required for the fine particles to shift is shortened,all the fine particles are allowed to sufficiently reach and contact thecathode; here, since the shifting speed of the fine particles hasvariations depending on factors, such as the particle size, thedifference in specific gravity between the fine particles and theplating solution, the increase in the specific gravity of the particlessubjected to the growth of plating, the viscosity of the platingsolution, and the filtering speed of the plating solution, it isappropriately determined based upon factors such as the particle size ofthe fine particles to be plated, the kind of the plating solution, thenumber of revolutions of the treatment chamber and the pore size of theporous member.

The fine particles used in the present inventions 14 and 15 are notparticularly limited, but include for example, metal fine particles,organic resin fine particles or inorganic fine particles. In the case ofthe application of the organic resin fine particles or the inorganicfine particles, the fine particles formed with a conductive base layeron its surface are preferably used. The electroless plating method ispreferably used as the formation method of the conductive base layer.However, it is not limited to this method, but other knownconductivity-applying methods may be adopted.

The above-mentioned metal fine particles are not particularly limited,but include for example, iron, copper, silver, gold, tin, lead,platinum, nickel, titanium, cobalt, chromium, aluminum, zinc, tungsten,and alloys thereof.

The above-mentioned organic resin fine particles are not limited butinclude fine particles comprising a linear polymer, or fine particlescomprising a network polymer, or fine particles comprising athermosetting resin, or fine particles made of an elastic member.

With respect to the linear polymer constituting the above-mentioned fineparticles comprising a linear polymer, it includes, nylon, polyethylene,polypropylene, methylpentene polymer, polystyrene,polymethylmethacrylate, polyvinyl chloride, polyvinylfluoride,polytetrafluoroethylene, polyethylene terephthalate,polybutyleneterephthalate, polysulfone, polycarbonate,polyacrylonitrile, polyacetal, polyamide, etc.

With respect to the network polymer constituting the above-mentionedfine particles comprising a network polymer, it includes, monopolymersof crosslinkable monomer, such as divinylbenzene, hexatoluene,divinylether, divinylsulfone, diallylcarbinol, alkylenediacrylate, oligoor poly(alkyleneglycol)diacrylate, oligo orpoly(alkyleneglycol)dimethacrylate, alkylenetriacrylate, alkylenetrimethacylate, alkylenetetraacrylate, alkylenetetramethacrylate,alkylenebisacrylamide, and alkylenebismethacylamide, or copolymers ofthese crosslinkable monomers and other polymerizable monomers. As aparticularly suitable polymerizable monomer, divinylbenzene,hexatoluene, divinylether, divinylsulfone, alkylenetriacrylate,alkylenetetraacrylate, etc. are more preferably used.

With respect to the thermosetting resin constituting the above-mentionedfine particle comprising a thermosetting resin, it includesphenol-formaldehyde resins, melamine-formaldehyde resins,benzoguanamine-formaldehyde resins, urea-formaldehyde resins, epoxyresins, etc.

With respect to the elastic member constituting the above-mentioned finecomprising an elastic member, for example, natural rubber, syntheticrubber, etc. are used.

With respect to the material for the inorganic fine particles, it is notparticularly limited, but include for example, silica, titanium oxide,iron oxide, cobalt oxide, zinc oxide, nickel oxide, manganese oxide,aluminum oxide, etc.

The particle size of the fine particles is preferably set in the rangeof 0.5 to 5000 μm, more preferably 0.5 to 2500 μm, and much morepreferably 1 to 1000 μm. The variation coefficient of the fine particlesis preferably set to not more than 50%, more preferably not more than35%, much more preferably 20%, and the most preferably not more than10%. Here, the variation coefficient means a value representing thestandard deviation by the use of percentage based upon the averagevalue; this is represented by the following formula:variation coefficient=(standard deviation of particle sizes/averagevalue of particle sizes)×100(%)

In general, the shifting speed of particles in a fluid receiving acentrifugal force have variations depending on the centrifugal effect,the difference in specific gravity between the particles and the fluid,the particle size and the viscosity of the fluid. For this reason, undera constant centrifugal effect, the greater the difference in specificgravity and the particle size, the faster the shifting speed.Accordingly, since the shifting speed of the particles becomes slower asthe particle size of the fine particles to be plated becomes smaller,the fine particles used in the present invention 14 and invention 15 arepreferably designed to have a greater difference in specific gravityfrom the plating solution.

With respect to the electroplating layer, it is not particularlylimited, but includes for example, an electroplating layer, etc.comprising at least one kind of metal selected from the group consistingof gold, silver, copper, platinum, zinc, iron, lead, tin, aluminum,cobalt, indium, nickel, chromium, titanium, antimony, bismuth,germanium, cadmium and silica.

Referring to Figures, the following description will discuss oneembodiment of a manufacturing method for conductive fine particles ofthe present inventions of 14 and 15.

FIG. 11 shows one example of a manufacturing device for conductive fineparticles that is preferably used in the manufacturing method forconductive fine particles in the present invention 14.

The manufacturing device for conductive fine particles, shown in FIG.11, comprises a disk-shaped bottom plate 10 secured to the upper end ofa perpendicular driving shaft 3; a porous member 21 that is placed onthe outer circumferential upper face of the bottom plate 10 and thatallows only a plating solution to pass there through; a contact ring 11for conducting electricity placed on the upper face of the porous member21; a hollow cover 1 having a trapezoidal cone shape with an opening 8on its upper center portion; a rotatable treatment chamber 13 formed ina manner so as to sandwich the porous member 21 and the contact ring 11between the outer circumferential portion of the hollow cover 1 and thebottom plate 10; a supply tube 6 for supplying the plating solution tothe treatment chamber 13 through the opening 8; a container 4 forreceiving the plating solution scattered from the pores of the porousmember 22; a drain tube 7 for draining the plating solution accumulatedin the container 4; and an electrode 2 inserted through the opening 8 tocontact the plating solution. Here, in the manufacturing device forconductive fine particles having the above-mentioned construction, thecontact ring 11 forms a cathode, the porous member 21 forms a filtersection, and the electrode 2 forms an anode.

The plating solution, subjected to a centrifugal force due to therotation of the driving shaft 3, is allowed to pass the porous member21, and scattered into the plastic container 4, with the result that theliquid level of the plating solution into the treatment chamber 13drops; therefore, in order to compensate for the reduction, the amountof the liquid is monitored by a level sensor 5 so that the platingsolution is supplied to the treatment chamber 13 from the supply tube 6for supplying the plating solution through the opening 8 and the liquidlevel into the treatment chamber 13 is always made to contact anelectrode 2 a. In FIG. 1, reference numeral 2 represents a positiveelectrode connected to the anode 2 a. Reference numeral 9 is a contactbrush. Here, a power supply used for the electrodes is not shown in theFigure.

In the present embodiment, the plating solution is supplied to thetreatment chamber 13 from the plating solution supply tube 6, fineparticles each having a conductive base layer formed thereon, arecharged into the treatment chamber 13 through the opening 8 of thehollow cover 1, and dispersed therein. Since the plating solution passesthrough the porous member 21 and goes out of the treatment chamber 13subjected to the rotation of the driving shaft 3, the plating solutionsupply tube 6 compensates for the amount of the reduction. Other platingconditions are not particularly distinct from general platingoperations.

The above-mentioned porous member 21 is a filter-shaped porous memberhaving communicating bubbles formed by plastics or ceramics, and thosehaving a pore size that allows only the plating solution such as aplating solution to pass there through, but does not allow fineparticles and conductive fine particles to do are adopted; and it ispreferred that those have a construction in which a filter sheet 20having a pore size that allows only a plating solution to pass therethrough is placed on the upper face of the plate-shaped porous support22.

In order to form a more uniform plating layer, it is preferable toreverse in its rotation direction or to stop the rotation of the drivingshaft 3 in each predetermined time. The number of revolutions and theoperation pattern may be the same in both of the forward rotation timeand the reverse rotation time, or may be different within the scope ofthe present invention.

Referring to a time chart of operation conditions shown in FIG. 2, thefollowing description will discuss one embodiment of a manufacturingdevice for conductive fine particles of the present invention in whichthe manufacturing device for conductive fine particles shown in FIG. 11is used.

First, organic resin fine particles having a specific gravity of 1.23and a particle size of 650 μm, each having an electroless nickel platinglayer formed on its surface, are loaded into the treatment chamber 13having a Watt bath having a specific gravity of 1.11 served as a platingsolution. In this case, the difference in specific gravity between thefine particles and the Watt bath is 0.05. Next, the treatment chamber 13is accelerated for one second. After the treatment chamber 13 hasreached a peripheral velocity of 226 m/min, it is rotated constantly atthis velocity. Three seconds after the start of the constant rotation (4seconds after the start of the rotation of the treatment chamber 13,that is, the particle shifting time is determined at 4 seconds), arectifier is turned on so that power application is started and aplating process is carried out. The power application time is 5 seconds.Thereafter, the treatment chamber 13 is decelerated in one second, andstopped for one second. These operations constitute one cycle, and thetreatment chamber 13 is reversed in its rotation for each cycle to carryout the plating process.

Here, in the manufacturing device for conductive fine particles used inthe present embodiment, the porous member 21 has a construction in whicha filter sheet 20 made from nylon having a pore size of 10 μm and athickness of 10 μm is affixed to the upper surface of a plate-shapedporous support 22 formed by high-density polyethylene having a pore sizeof 100 μm and a thickness of 6 mm.

The present invention 16 relates to conductive fine particles, and ananisotropic, a conductive adhesive and a conductive connecting elementutilizing the particles.

The conductive fine particles of the present invention 16 has a particlesize in the range of 0.5 to 5000 μm. When particles having a particlesize of less than 0.5 μm exist, the conductive fine particles are notallowed to contact the electrodes to be connected between these,resulting in a gap between the electrodes and the subsequentmalconnection. The particle size exceeding 5000 μm fails to make aminute conductive connection; thus, it is limited to the above-mentionedrange.

This is preferably set in the range of 0.5 to 2500 μm, more preferably 1to 1000 μm, much more preferably 5 to 300 μm, in particular preferably10 to 100 μm, and the most preferably 20 to 50 μm.

The conductive fine particles of the present invention 16 has avariation coefficient of not more than 50%. The variation coefficient isrepresented by the following formula:(σ/Dn)×100σ represents the standard deviation of the particle size, and Dnrepresents the number average particle size.

The variation coefficient exceeding 50% makes the particles ununiform,with the result that upon making the electrodes contact with each otherthrough the conductive fine particles in a step described later, a greatnumber of particles are left untouched, thereby causing the possibilityof leakage between the electrodes; therefore, it is limited to theabove-mentioned range.

This is preferably set at not more than 35%, more preferably not morethan 20%, much more preferably not more than 10%, and the mostpreferably not more than 5%.

The conductive fine particles of the present invention 16 has an aspectratio of less than 1.5. The aspect ratio refers to a value that isobtained by dividing the average major diameter by the average minordiameter of particles. The aspect ratio not less than 1.5 makes theparticles ununiform, with the result that upon making the electrodescontact with each other through the conductive fine particles, a greatnumber of particles are left untouched, thereby causing the possibilityof leakage between the electrodes; therefore, it is limited to theabove-mentioned range.

This is more preferably set to less than 1.1, more preferably less than1.05.

The above-mentioned particle size, aspect ratio and variationcoefficient related to the conductive fine particles of the presentinvention 16 can be measured by observation using an electronicmicroscope.

The conductive fine particles of the present invention 16 are notparticularly limited as long as they are particles whose outer surfaceis plated; and, for example, those coated with an organic compound, aresin, or an inorganic substance, etc. may be used.

The conductive fine particles of the present invention 16 allow electriccurrents to flow from one of the electrodes to the other when pressed ina sandwiched manner between a plurality of electrodes, and since theirouter surface is plated, the current capacity upon connection isincreased.

The above-mentioned plating is preferably carried out by using a noblemetal. In the case of plating without noble metal, oxidation occurs onthe contact face to the electrode when exposed to heating and coolingcycles or a high temperature and high moisture state for a long time,resulting in an extreme increase in the connection resistivity and thesubsequent degradation in reliability. With respect to theabove-mentioned noble metal, in particular, gold, platinum and palladiumare preferably used.

The above-mentioned plating may be curried out with a low-melting-pointmetal having a melting point of not more than 300° C., such as, forexample, solder and a tin alloy. In this case, in order to obtain asufficient metal bonding, the thickness of the plating is set topreferably not less than 0.2 μm, and more preferably 3 to 30 μm.

In the case when the outer surface of each of the conductive fineparticles of the present invention 16 is subjected to plating, aconductive layer formed by the electroless plating and the like ispreferably formed as a base layer and from the viewpoint of conductivityand easiness in plating, the conductive layer is preferably provided bythe electroless plating using nickel, copper, or silver.

When the outer surface of each of the conductive fine particles of thepresent invention 16 is subjected to plating, an electroplating ispreferably adopted as the plating, and the method of the electroplatingis not particularly limited; and with viewpoint of carrying out moreuniform plating easily, a rotatable plating device, which has a cathodeon the outer circumferential portion thereof and an anode placed so asnot to contact the cathode, is preferably used to carry out theelectroplating. More preferably, a plating device, which has a filtersection on its outer circumferential portion and carries out platingwhile rotating and supplying a plating solution, is used to carry outthe electroplating.

In the above-mentioned plating, the thickness of the plating is set inthe range of 0.001 to 50 μm. The thickness less than 0.001 μm fails toobtain a sufficient electric capacity, and the thickness exceeding 50 μmfails to sufficiently demonstrate the performance of the base material.More preferably, it is set in the range of 0.01 to 10 μm, and much morepreferably 0.2 to 3 μm. With viewpoint of obtaining uniform particles,the variation coefficient of the plating thickness is set to not morethan 20%, and more preferably not more than 10%.

The base material of the conductive fine particles of the presentinvention 16 is not particularly limited, but includes, resins,inorganic particles, metal particles, and mixtures thereof. Inparticular, those having a K value of 200 to 2000 kgf/m², and morepreferably 300 to 500 kgf/m², a recovery rate of not less than 10%, andmore preferably, not less than 50%, a variation coefficient of particlesize of not less than 5% and an aspect ratio of less than 1.05 arepreferably used. In the case of low K value and recovery rate,malconnection may occur due to impacts and cooling and heating cycles.In contrast, in the case of a high K value, the electrodes may bedamaged.

The anisotropic conductive adhesive of the present invention 16 isobtained by dispersing the conductive fine particles of the presentinvention 16 in an insulating resin. The anisotropic conductive adhesiveincludes an anisotropic conductive film, anisotropic conductive paste,anisotropic conductive ink, etc.

With respect to a binder resin for the anisotropic conductive adhesive,not particularly limited, but includes for example, thermoplastic resinssuch as acrylic resins, ethylene-vinylacetate copolymerization resin andstyrene-butadiene block copolymer resin, and compositions set by heatand/or light, such as setting agents and setting resin compositions ofmonomers and oligomers having a glycidyl group and isocyanate.

The thickness of a coat film of the anisotropic conductive adhesive ispreferably set to 10 to several hundreds μm.

With respect to an object to be connected by using the anisotropicconductive adhesive of the present invention 16, there can be mentionedparts and the like of substrates and semiconductors. Electrode sectionsare respectively formed on the surface of these parts. The presentinvention 16 includes constructions connected by the anisotropicconductive adhesive of the present invention 16.

The above-mentioned substrates are classified into flexible substratesand rigid substrates. A resin sheet having a thickness of 50 to 500 μmis used as the flexible substrate, and, for example, polyimide,polyamide, polyester, polysulfone, etc. are used as the resin sheet.

The above-mentioned rigid substrates are classified into those formed byresins and those formed by ceramics. Examples of those formed by resinsinclude glass fiber reinforced epoxy resins, phenol resins, cellulosefiber reinforced phenol resins, etc. Examples of those formed byceramics include silicon dioxide, alumina, etc.

The above-mentioned substrate structure may be a mono-layer structure,or a multi-layer substrate in which a plurality of layers are formed,for example, by means of formation of through holes, etc., withelectrical connection being made with each other, in order to increasethe number of electrodes per unit area.

With respect to the above-mentioned parts, they are not particularlylimited, but include example, active parts for semiconductors, etc.,such as transistors, diodes, ICs and LSIs, and passive parts, etc., suchas resistors, capacitors and quartz oscillators.

Electrodes are formed on the surface of each of the above-mentionedsubstrates and parts. The shape of the above-mentioned electrodes is notparticularly limited but includes those having a striped shape, a dotshape, or a desired shape, are used.

With respect to the material of the electrodes, examples thereof includegold, silver, copper, nickel, palladium, carbon, aluminum, ITO, etc. Inorder to reduce its contact resistivity, those having a gold coat oncopper, nickel, etc., may be used.

The thickness of the electrodes is preferably set in the range of 0.1 to100 μm. The width of the electrodes is preferably set in the range of 1to 500 μm.

The conductive fine particles of the present invention 16 may bedispersed at random in the anisotropic conductive adhesive of thepresent invention 16, or may be placed at specific positions. In thecase of the random dispersion, the electrodes can be generallyelectrically connected in a universal manner, and in particular, in thecase of the specific distribution, electrical connection can be madeefficiently.

The method for electrically connecting the opposing two electrodes withopposite phases by using the conductive fine particles in the presentinvention 16 may be a method in which the anisotropic conductiveadhesive, the binder resin and the conductive fine particles are used ina separated manner.

With respect to the method for using the anisotropic conductive adhesiveof the present invention 16, for example, on a substrate or a parthaving electrodes formed on its surface, the anisotropic conductive filmof the present invention 16 is placed, and a substrate or a part havingan opposing electrode face is then placed, and followed by heating andpressing. In place of the anisotropic conductive film, a predeterminedamount of the anisotropic paste may be applied by a printing means suchas screen printing and a dispenser. In the above-mentioned heating andpressing processes, a pressing device, a bonding machine, etc., having aheater, are used.

A method without using the anisotropic conductive film or theanisotropic conductive paste may be proposed, for example, a methodwherein liquid binder is injected into a gap between the two electrodesections joined by using the conductive fine particles, and followed bycuring. In the connection structure obtained by the above-mentionedmethod, since electroplating particles having a superior conductiveproperty are used as the conductive fine particles, a greater electriccurrent can be stably provided.

Moreover, by the application of particles having an appropriate averageparticle size, leakage hardly occurs on the opposing electrodes withopposing phases, and by limiting the variation coefficient and aspectratio, non-contact particles are hardly generated so that leakage hardlyoccurred between the electrodes, when making the electrodes contact witheach other through the conductive fine particles.

Furthermore, in the case of noble metal or low-melting-point metalplating, even when exposed to heating and cooling cycles or ahigh-temperature, high moisture state for a long time, oxidation hardlyoccurs on the contact face, etc. to the electrodes; therefore, it is notlikely to occur large increase in the connection resistivity, ordegradation in the reliability. Therefor, the reliability for a longtime can be ensured even under such conditions.

The following description will discuss the electronic circuit parts,etc. of the present invention 17. Hereinafter, the simple term “thepresent invention” refers to the electronic circuit parts, the relatedelectronic circuit substrates, the electronic circuit elements, etc. ofthe present invention 17.

In the present specification, “electronic circuit elements” refer tosemiconductor elements having electrodes formed thereon, and forexample, diodes, transistors, ICs, LSIs, SCRs (Silicon ControlledRectifier), photoelectric elements, solar batteries, light-emittingdiodes (LED), etc. are listed. In particular, examples of ICs includebear chips, package type ICs, chip size packages (CSP), etc., and alsoinclude hybrid ICs and multi chip modules (MCM) that are manufactured incombination with elements other than semiconductors, such as resistors,capacitors, inductors and quartz oscillators.

Electrodes for the above-mentioned electronic circuit elements aremanufactured by, for example, the vapor deposition method or thesputtering method, and examples of the material for the electrodesinclude metals such as aluminum and copper, and alloys such asnickel-chromium-gold, nickel-chromium-copper, chromium-gold,nickel-chromium-palladium-gold, nickel-chromium-copper-palladium-gold,molybdenum-gold, titanium-palladium-gold, titanium-platinum-gold, etc.

With respect to the layout of the electrodes on the electronic circuitelement, those of the peripheral type and the area type or the mixedtype thereof can be mentioned.

In the present specification, “electronic circuit substrates” meansthose substrates having electrodes formed thereon which are used byplacing the above-mentioned electronic circuit elements thereon, andexamples thereof include; printed wiring substrates formed by paperphenol resin, glass epoxy resin, or glass polyimide resin, as a base;flexible printed wiring substrates formed by polyimide, or saturatedpolyester resin; and ceramics substrates. Moreover, they also includepackages formed by resins or ceramics which are used for packaging bearchips.

In the present specification, “electronic circuit parts” refer to thoseparts that are constituted by the electronic circuit substrates on whichthe above-mentioned electronic circuit elements are placed and that areutilized as parts in the electronics field, and with respect to thepackaging system used in their manufacturing process, for example, flipchips, BGAs, etc. are preferably used.

The present invention 17 relates to an electronic circuit part which isformed by electrically connecting electrode sections of an electroniccircuit element and electrode sections of an electronic circuitsubstrate, wherein the connection is formed by applying a laminatedconductive fine particle provided with a conductive metal layer on thesurface of each of spherical elastic base particles, at each connectingsection between the electrode section of the electronic circuit elementand the electrode section of the electronic circuit substrate, theelectrical connection is formed by a plurality of laminated conductivefine particles per connecting section, and the connection is formed byusing double laminated conductive fine particles provided with theconductive metal layer around each of the spherical elastic baseparticles, a low-melting-point metal layer around the conductive metallayer, and at each connecting section between the electrode section ofthe electronic circuit element and the electrode section of theelectronic circuit substrate, the electrical connection is formed by aplurality of laminated conductive fine particles per connecting section.

Moreover, the present invention 17 also relates to the above-mentionedelectronic circuit part wherein the thickness of the conductive metallayer (t: unit mm) is represented by the following [formula 1].P×D/σ<t<0.2×D  [Formula 1]

where P is a constant based on pressure unit, 0.7 Kg/mm², D is thediameter (unit: mm) of an elastic base particle, and σ is a tensilestrength (unit: Kg/mm²) of a metal material forming the conductive metallayer, the tensile strength being measured under the condition that thesheet-shaped material having a thickness of 0.5 to 2 mm is tested at atensile speed of 10 mm/min. by a tensile tester.

The present invention 17 relates to an electronic circuit part that isformed by electrically connecting electrode sections of an electroniccircuit element and electrode sections of an electronic circuitsubstrate, wherein the connection is formed by applying laminatedconductive fine particles provided with a conductive metal layer aroundeach of spherical elastic base particles, at each contact sectionbetween the conductive metal layer of the laminated conductive fineparticle and the electrode section of the electronic circuit element,the electrical connection is formed by one laminated conductive fineparticle per each contact section, and at each contact section betweenthe conductive metal layer of the laminated conductive fine particle andthe electrode section of the electronic circuit substrate, theelectrical connection is formed by one laminated conductive fineparticle per each contact section, and the above-mentioned connection isformed by using double laminated conductive fine particles provided withthe conductive metal layer around each of the spherical elastic baseparticles and a low-melting-point metal layer around the conductivemetal layer, and at each contact section between the conductive metallayer and the low-melting-point metal layer of the double laminatedconductive fine particle and the electrode section of the electroniccircuit element, the electrical connection is formed by one doublelaminated conductive fine particle per contact section, and at eachcontact section between the conductive metal layer of the doublelaminated conductive fine particle and the electrode section of theelectronic circuit substrate, the electrical connection is formed by onedouble laminated conductive particle per each contact section.

In the present invention 17, the laminated conductive fine particlesand/or the double laminated conductive fine particles are used. In thepresent specification, the laminated conductive fine particles and thedouble laminated conductive fine particles are also collectivelyreferred to as conductive fine particles. The above-mentioned laminatedfine particle comprises a spherical elastic base particle 111 and aconductive metal layer 2 (FIG. 39). The above-mentioned double laminatedconductive fine particle comprises a spherical elastic base particle111, a conductive metal layer 222 and a low-melting-point metal layer333 (FIG. 40).

With respect to the spherical elastic base particle, it is notparticularly limited as long as it is a material having elasticity, andexamples thereof include particles formed by a resin material or anorganic-inorganic hybrid material, etc. The resin material is notparticularly limited, but includes for example, linear copolymers suchas polystyrene, polymethylmethacrylate, polyethylene, polypropylene,polyethyleneterephthalate, polybutyleneterephthalate, polysulfone,polycarbonate, and polyamide; and divinylbenzene, hexatoluene,divinylether, divinylsulfone, diallylcarbinol, alkylenediacrylate, oligoor polyalkylene glycoldiacrylate, oligo or polyalkyleneglycoldimethacrylate, alkylenetriacrylate, alkylenetetraacrylate,alkylenetrimethacylate, alkylenetetramethacrylate,alkylenebisacrylamide, and alkylenebismethacylamide, and networkpolymers obtained by polymerizing both-ends acryl denaturedpolybutadiene oligomer solely or together with other polymerizablemonomer.

With respect to particles formed by the resin material, it is notparticularly limited, but includes for example, thermosetting resinssuch as phenol-formaldehyde resins, melamine-formaldehyde resins,benzoguanamine-formaldehyde resins, urea-formaldehyde resins.

With respect to the organic-inorganic hybrid material, for example, thefollowing materials are used: those materials obtained by forming acopolymer between acrylate or methacrylate with a silyl group on itsside chain and a vinyl monomer such as styrene and methylmethacrylate,and then allowing the silyl group to undergo a condensation reaction;those materials obtained by allowing tetraethoxysilane, triethoxysilane,or diethoxysilane to undergo a sol-gel reaction in the coexistence of anorganic polymer; and those materials obtained by allowingtetraethoxysilane, triethoxysilane, or diethoxysilane to undergo asol-gel reaction, and then baking this at a low temperature, therebyallowing the organic components to remain.

The particle size of the spherical elastic base particles is preferablyset to 5 to 700 μm, and more preferably 10 to 150 μm.

With respect to the particle size distribution of the spherical elasticbase particles, a variation coefficient [(standard deviation)/(averageparticle size)×100] is preferably not more than 5%, and more preferablynot more than 3%.

The above-mentioned spherical elastic base particles are preferablydesigned to have a thermal conductivity of not less than 0.30 W/m·K.

The conductive fine particles used in the invention 17 are allowed toexert a superior performance when the thickness of the conductive metallayer (t: mm) satisfies the following [formula 1].P×D/σ<t<0.2×D  [Formula 1]

where P is a constant based on pressure unit, 1.0 Kg/mm², D is thediameter (unit: mm) of an elastic base particle, and σ is a tensilestrength (unit: Kg/mm²) of a metal material forming the conductive metallayer, and the tensile strength is measured under the condition that thesheet-shaped material having a thickness of 0.5 to 2 mm is tested at atensile speed of 10 mm/min. by a tensile tester.

Thus, in the case of the thickness t of the conductive metal layer ofnot more than P×D/σ, the conductive metal layer is not allowed to resistthe thermal expansion of the elastic base particles upon heatapplication, and the degradation in performance such as cracking andfatigue destruction is consequently occurred. In contrast, in the caseof the thickness t of not less than 0.2×D, in response to the shearingstress that the conductive fine particles receive, which will bedescribed later, the elastic base particles hardly receive an elasticshearing deformation beyond its recovery, with the result that anexcessive stress is applied to the connection section between theconductive metal layer of the conductive fine particles and theelectronic circuit element as well as the conductive circuit substrate,resulting in degradation in the connecting reliability.

Since the lower limit value of the thickness t of the conductive metallayer is represented by P×D/σ, this is inversely proportional to thetensile strength of the conductive metal layer; therefore, the more thetensile strength increases, the lower limit value decreases. In the caseof formation of the conductive metal layer formed by nickel, since thetensile strength is approximately 85 Kg/mm², P×D/σ is approximately0.0012 mm in the case when D is 100 μm.

The kind of the metal constituting the conductive metal layer is notparticularly limited, but includes for example, those materialscontaining at least one kind selected from the following groupconsisting in nickel, palladium, gold, silver, copper, platinum, andaluminum.

With respect to the conductive metal layer, those comprising a pluralityof metal layers provide desirable results, as compared with those madeof a single metal layer.

With respect to the formation method of the conductive metal layer, dryplating methods such as vacuum vapor deposition and sputtering, and wetplating methods such as electroless plating and electroplating, areused. In particular, the wet plating methods are more preferably used,and the most preferable results are obtained when a metal layer formedby electroless plating and a metal layer formed by electroplating areconcomitantly used.

The above-mentioned electroplating is carried out by using a platingdevice as illustrated in FIG. 41. Thus, the electroplating layer isformed on the surface of each particle by plating process, wherein theplating device comprises a disk-shaped bottom plate secured to the upperend of a perpendicular driving shaft; a porous member that is placed onthe outer circumferential upper face of the bottom plate and that allowsonly a plating solution to pass there through; a contact ring forconducting electricity placed on the upper face of the porous member; ahollow cover of a trapezoidal cone shape having an opening on its uppercenter portion, to the upper end of which a hollow cylinder having thesame pore diameter as the opening diameter is joined, with the upper endof the hollow cylinder being bent toward the inner wall side of thehollow cylinder; a rotatable treatment chamber formed in a manner so asto sandwich the porous member and the contact ring between the outercircumferential portion of the hollow cover and the bottom plate; asupply tube for supplying the plating solution to the treatment chamberthrough the opening; a container for receiving the plating solutionscattered from the pores of the porous member; a drain tube for drainingthe plating solution accumulated in the container; and an electrodeinserted through the opening to contact with the plating solution, andin this device, spherical elastic base particles, which have beenpreliminarily subjected to a pre-treatment, for example, an electrolessplating process, are loaded into the treatment chamber, and a platingprocess is carried out by rotating the treatment chamber centered on itsrotation shaft while a plating solution is being supplied to thetreatment chamber and power is being applied thereto.

The low-melting-point metal layer is preferably formed with a thicknessof 3 to 50% of the particle size of the spherical elastic base particle.The thickness exceeding 50% causes not only a reduction in the elasticproperty of the conductive fine particles, but also a problem in whichupon melting down, the low-melting-point metal layer shifts in thehorizontal direction resulting in a bridge phenomenon between theadjacent electrodes. In contrast, the thickness of the low-melting pointmetal layer of less than 3% sometimes cause a problem of weak connectingstrength between the conductive metal layer of the conductive fineparticles and the electrode section of the electronic circuit element orthe conductive circuit substrate.

The above-mentioned low-melting-point metal layer is formed by metalshaving a melting point of not more than 260° C. Examples of thelow-melting-point metals include not less than one element selected fromthe group consisting of tin, lead, bismuth, silver, zinc, indium, andcopper. In the case when an alloy layer is used as the low-melting-pointmetal layer, the low-melting-point metal layer containing tin as itsmain component is preferable, and that containing tin as the maincomponent and not less than one element selected from the groupconsisting of lead, bismuth, silver, zinc, indium and copper, is morepreferable. The low-melting-point metal layer may comprise a pluralityof metal layers.

The formation of the low-melting-point metal layer is carried out byusing wet plating methods such as electroless plating andelectroplating, and in particular, the electroplating method ispreferably used together with the above-mentioned electroplating device.

Next, the following description will discuss a manufacturing method foran electronic circuit part using the above-mentioned conductive fineparticles.

In the case when an electronic circuit part comprising the electroniccircuit elements and the electronic circuit substrates is manufacturedby using the laminated conductive fine particles provided with theconductive metal layer around each of the spherical elastic baseparticles, a conductive material, formed by either a conductive adhesiveor cream solder, is placed on either of the electrode sections of theelectronic circuit element or the electrode section of the electroniccircuit substrate, and the conductive fine particles are placed on saidelectrode section, and then the conductive metal layer of the conductivefine particles and the electrode section are electrically connected byheating. FIG. 41 schematically shows the electronic circuit element onwhich the laminated conductive fine particles are placed. Moreover, FIG.42 schematically shows the electronic circuit substrate on which thelaminated conductive fine particles are placed.

Next, the conductive material comprising either a conductive adhesive orcream solder is placed on the other electrode section of the electroniccircuit element or the electrode section of the electronic circuitsubstrate, and this is then superposed on the conductive fine particleswhich have already been joined, and heated; thus, electrical connectionis formed. In this manufacturing process, since it is not necessary toapply any high pressure, no damage is given to the performance of the ICchip. Upon placing the laminated conductive fine particles on either ofthe electrode sections of the electronic circuit element or theelectrode section of the electronic circuit substrate, a mold havingrecesses each of which is smaller than the diameter of the conductivefine particle is placed on the position corresponding to the electrodesection of either the electrode circuit element or the electrode sectionof the electronic circuit substrate, and the conductive fine particlesare positioned on the recesses of this mold. Next, after adhering liquidhas been applied to one portion of the exposed surfaces of theconductive fine particles positioned on the mold, the conductive fineparticles are transferred on the electrode section by allowing the moldto contact the one of the electrode sections. Accordingly, theconductive fine particles are not placed at positions other than theelectrode sections, and a reduction in the insulating resistivitybetween the adjacent electrodes can be prevented.

Moreover, in the case when an electronic circuit part comprising theelectronic circuit elements and the electronic circuit substrates ismanufactured by using the double laminated conductive fine particlesprovided with the conductive metal layer and the low-melting-point metallayer around each of the spherical elastic base particles, the doublelaminated conductive fine particles are first placed on either theelectrode section of the electronic circuit element or the electrodesection of the electronic circuit substrate, and by heating to thevicinity of the electrode section on which the double laminatedconductive fine particles are placed, the low-melting-point metal layerof the double laminated conductive fine particle is allowed to melt downso that the conductive metal layer of the double laminated conductivefine particle and the electrode section are electrically connected. FIG.43 schematically illustrates the electronic circuit element on which thedouble laminated conductive fine particles are placed. Moreover, FIG. 44schematically illustrates the electronic circuit substrate on which thedouble laminated conductive fine particles are placed.

Next, by cooling while the electric connection is maintained, theelectric connection is secured, and the other electrode section issuperposed onto the double laminated conductive fine particles securedon the one of the electrode section and heated so that thelow-melting-point metal layer is allowed to melt down and the otherelectrode section and the double laminated conductive fine particlessecured on the electrode section are electrically connected, and thenthe connection is maintained to be secured, by cooling. In thismanufacturing process also, it is not necessary to apply any highpressure.

In the case when the double laminated conductive fine particles areplaced on either the electrode section of the electronic circuit elementor the electrode section of the electronic circuit substrate, theabove-mentioned mold is also used in the same manner as the case inwhich the laminated conductive fine particles are placed.

With respect to another manufacturing method for electronic circuitparts, a method has been proposed, in which onto either the electrodesection of the electronic circuit element or the electrode section ofthe electronic circuit substrate, one conductive fine particle, coatedwith a conductive metal layer around the periphery of a sphericalelastic base particle, is heated and pressed to be placed thereon; thus,the conductive metal layer of the conductive fine particle and theelectrode section are allowed to maintain the electric connection by theconductive material.

In the electronic circuit part manufactured as described above, theabove-mentioned connection is formed by using the conductive fineparticles provided with the conductive metal layer or the conductivemetal layer and the low-melting-point metal layer around the sphericalelastic base particle, and at the connecting section between theconductive metal layer of the conductive fine particle and the electrodesection of the electronic circuit element, connection is electricallyformed by a conductive fine particle per a contact section, and at theconnecting section between the conductive metal layer of the conductivefine particle and the electrode section of the electronic circuitsubstrate, connection is electrically formed by one conductive fineparticle per each contact section.

FIG. 45 schematically shows an electronic circuit part of the presentinvention.

In this electronic circuit part, upon heating or cooling, of theelectrode section of the electronic circuit element and the baseelectrode section of the electronic circuit substrate, one is dislocatedin parallel with the other due to the difference in the thermalexpansion coefficient between the above-mentioned electronic circuitelement and the electronic circuit substrate.

For this reason, the conductive fine particles are subjected to ashearing deformation, but in this case, since the spherical elastic baseparticle is elastically subjected to the shearing deformation, and thisdeformation can be recovered in the electronic circuit part using theconductive fine particles, a shearing stress, exerted on the connectinginterface between the conductive metal layer of the conductive fineparticles and the electrode section of the electronic circuit element orthe electrode section of the electronic circuit substrate, is reduced,thereby improving the connecting reliability.

This reducing effect to the shearing stress can be measured andevaluated by using a bonding tester (PTR-10 type, Leska K.K.). Withrespect to the measurement samples, the conductive fine particlesconnected to and secured on the electronic circuit substrates are used.The electronic circuit substrate to which the conductive fine particlesare connected and secured is attached to a stage, a tool for shear testis placed perpendicular to the stage, and while keeping in contact withthe side face of the conductive fine particles, the stage is shifted sothat a shearing stress is exerted on the connecting interface betweenthe conductive metal layer of the conductive fine particles and theelectrode section of the electronic circuit substrate.

The amount of elastic strain that can be recovered represents thecapability of recover from the shearing deformation. Here, in theconductive fine particles of the present invention, the base particleshaving a sufficient elasticity are used; therefore, the elastic strainthat can be recovered is greater so that a greater capability of recoverfrom the shearing deformation can be provided.

In the electronic circuit part of the present invention, even in thecase when, of the electrode section of the electronic circuit elementand the electrode section of the electronic circuit substrate, one isdislocated in parallel with the other due to the physical force ofparallel direction, since the conductive fine particles of the presentinvention have a greater recovering capability from shearingdeformation, they can be recovered even upon receipt of such adislocation, thereby providing high connecting reliability.

Moreover, in the electronic circuit part of the present invention, theconductive fine particles which contain base particle having asufficient elasticity are used; therefore, since the peel strength Ffrom the electrode section against the strain deformation of theconductive fine particles is great as shown in the following [formula2], the conductive fine particles are hard to peel even upon receipt ofa great dislocation, thereby maintaining the electrical connection, andconsequently to provide high connecting reliability.500×D′×D′ (gr/mm·mm)<F<8000×D′×D′ (gr/mm·mm)  [Formula 2]

wherein D′ represents the diameter (unit: mm) of the conductive fineparticles.

In the electronic circuit part of the present invention, the distancebetween the electrode section of the electronic circuit element and theelectrode section of the electronic circuit substrate is preferably setto 90 to 100% of the diameter of the conductive fine particles.

In the case of the distance of less than 90%, the distance between theelectrode section of the electronic circuit element and the electrodesection of the electronic circuit substrate is too close, sometimesresulting in deformation of the conductive fine particles and thesubsequent deterioration in the electrical connection. When the distanceexceeds 100%, the conductive fine partices is likely to run det contactdeterioration with the electronic circuit element or the electroniccircuit substrate, thereby deterioration in the electrical connectionmay occur.

Moreover, in the electronic circuit part of the present invention, thelimit value of the current flowing between the electrode section of theelectronic circuit element and the electrode section of the electroniccircuit substrate is extremely great, that is, 0.5 to 10 Amp perelectrode section; therefore, even in the case of a large currentflowing between these electrodes, no damage is given to the electrodesections and the conductive fine particles, thereby ensuring highreliability. Moreover, in the present invention, connection is formed byusing flip chip bonding and BGA bonding as well as using the conductivefine particles; therefore, so that high-density wiring to the electroniccircuit element and the electronic circuit substrate can be provided.

BEST MODE FOR CARRYING OUT THE INVENTION

The following description will discuss the present invention in detailby means of examples; however, the present invention is not intended tobe limited only by these examples.

EXAMPLE 1

A nickel plating layer is formed as a conductive base layer on each oforganic resin fine particles obtained by copolymerizing styrene anddivinylbenzene; thus, a nickel plating fine particle having an averageparticle size of 75.72 μm and a standard deviation of 2.87 μm wasobtained. The resulting nickel plating fine particles (16 g) weresubjected to nickel plating on their surface by using a manufacturingdevice for conductive fine particles shown in FIG. 1.

With respect to the porous member 12, a porous member having a pore sizeof 20 μm, formed by high-density polyethylene, was used. Metal nickelwas used as the anode 2 a.

A Watt bath was used as the plating solution. The composition of theapplied Watt bath had a nickel concentration of 42 g/L, nickel sulfate150 g/L, and boric acid 31 g/L.

Power was applied across the electrodes with a voltage of 14 to 15 V for25 minutes, under the conditions that the temperature of the platingsolution was 50° C., the current was 30 A, and the current density was0.3 A/dm². The peripheral velocity of the treatment chamber was set at300 m/min, and the rotation direction was reversed every 11 seconds.

During the rotation of the treatment chamber, the plating solution,which was subjected to a force in the outer circumferential directiondue to the effect of a centrifugal force, formed a vortex having amortar-like shape; however, there was no overflowing from the upperopening of the hollow cover 1.

The nickel plated resin fine particles having a nickel plated layer asthe outermost layer thus obtained were observed under a microscope, andall the particles existed as individually isolated particles without anyaggregation. Moreover, the average particle size of 100 of the nickelplated resin fine particles was 78.52 μm and the thickness of the nickelplated layer was 1.4 μm. The variation coefficient of the particle sizewas 2.7%, thereby indicating that the thickness of the nickel platedlayer was extremely uniform.

Here, clogging occurred in the porous member, resulting in a particleloss of approximately 30%. After the plating test was repeated threetimes, clogging occurred too much, with the result that the porousmember was no longer usable.

EXAMPLE 2 (COMPARATIVE EXAMPLE)

Plating was carried out in the same manner as Example 1 except that aconventional manufacturing device for conductive fine particles shown inFIG. 2 was used as the plating device, and that as illustrated in FIG.8, a porous member, which was formed by affixing a nylon filter having apore size of 10 μm onto the inner side surface on the treatment chamberside of a porous member having a pore size of 70 μm made frompolypropylene, was used as the porous member 12.

When the treatment chamber was rotated, the plating solution, which wassubjected to a force in the outer circumferential direction due to theeffect of a centrifugal force, formed a vortex having a mortar-likeshape, and rose gradually along the inner wall of the cover 1, with theresult that the liquid was scattered from the opening 8 of the cover 1;consequently, the fine particles flowed (overflow) out of the treatmentchamber together with the scattering plating solution, as a resultfailing to carry out plating.

However, after completion of the plating process, no clogging was foundin the porous member.

Here, this Example 2 should be described as a comparative example.

EXAMPLE 3

Plating was carried out in the same manner as Example 1 except that amanufacturing device for conductive fine particles shown in FIG. 1 wasused as the manufacturing device for conductive fine particles, and thatas illustrated in FIG. 8, a porous member, which was formed by affixinga nylon filter having a pore size of 10 μm onto the inner side surfaceon the treatment chamber side of a porous member having a pore size of70 μm made from polypropylene, was used as a porous member 12.

During the rotation of the treatment chamber, the plating solution,which was subjected to a force in the outer circumferential directiondue to the effect of a centrifugal force, formed a vortex having amortar-like shape; however, there was no overflowing from the upperopening of the hollow cover 1.

The nickel plated resin fine particles having a nickel plated layer asthe outermost layer thus obtained were observed under a microscope, andall the particles existed as individually isolated particles without anyaggregation. Moreover, the average particle size of 100 of the nickelplated resin fine particles was 78.72 μm and the thickness of the nickelplated layer was 1.5 μm. The variation coefficient of the particle sizewas 2.6%, thereby indicating that the thickness of the nickel platedlayer was extremely uniform.

Here, no clogging was found in the porous member 12, and even after theplating test had been repeated five times, no clogging was found.

EXAMPLE 4

A nickel plating layer was formed as a conductive base layer on each oforganic resin fine particles obtained by copolymerizing styrene anddivinylbenzene; thus, a nickel plating fine particle having an averageparticle size of 250.68 μm and a standard deviation of 8.02 μm wasobtained. The resulting nickel plating fine particles (30 g) weresubjected to nickel plating on their surface by using a manufacturingdevice for conductive fine particles shown in FIG. 1.

With respect to the porous member 12, a porous member having a pore sizeof 70 μm, formed from polypropylene, was used. Metal nickel was used asthe anode 2 a. A Watt bath was used as the plating solution.

Power was applied across the electrodes with a voltage of 16 to 17 V for20 minutes, under the conditions that the temperature of the platingsolution was 50° C., the current was 38 A, and the current density was0.65 A/dm². The peripheral velocity of the treatment chamber was set at250 m/min, and the rotation direction was reversed every 11 seconds.

The nickel plated resin fine particles having a nickel plated layer asthe outermost layer thus obtained were observed under a microscope, andall the particles existed as individually isolated particles without anyaggregation. Moreover, the average particle size of 100 of the nickelplated resin fine particles was 255.68 μm and the thickness of thenickel plated layer was 2.5 μm. The variation coefficient of theparticle size was 2.4%, thereby indicating that the thickness of thenickel plated layer was extremely uniform. Here, the total plating timewas approximately 45 minutes.

EXAMPLE 5

The conductive fine particles (28 g) obtained in Example 3 weresubjected to solder plating on their surface by using the manufacturingdevice for conductive fine particles shown in FIG. 1.

With respect to the porous member 12, a porous member having a pore sizeof 20 μm, formed from high-density polyethylene, was used.

An alloy of tin (Sn):lead (Pb)=6:4 was used as the anode 2 a.

Acid bath (537A) made by Ishihara Chemical Co., Ltd. was used as theplating solution. The composition of the plating solution was adjustedso that the total metal concentration was set in the range of 15 to 30g/L, the metal ratio in the bath, Sn %=55 to 70%, alkanol sulfonic acid,100 to 150 g/L, and an additive, 40 mL. The results of analysis on theplating solution showed that the total metal concentration was 21 g/L,the metal ratio in the bath, Sn %=65%, and alkanol sulfonic acid, 107g/L.

Power was applied across the electrodes with a voltage of 7 to 8 V for15 minutes, under the conditions that the temperature of the platingsolution was 20° C., the current was 50 A, and the current density was0.5 A/dm². The peripheral velocity of the treatment chamber was set at300 m/min, and the rotation direction was reversed every 11 seconds.

During the rotation of the treatment chamber, the plating solution,which was subjected to a force in the outer circumferential directiondue to the effect of a centrifugal force, formed a vortex having amortar-like shape; however, there was no overflowing from the upperopening of the hollow cover 1.

The solder plated resin fine particles having a solder plated layer asthe outermost layer thus obtained were observed under a microscope, andall the particles existed as individually isolated particles. Moreover,the average particle size of 100 of the solder plated resin fineparticles was 84.88 μm and the thickness of the solder plated layer was3.2 μm. The variation coefficient of the particle size was 3.2%, therebyindicating that the thickness of the nickel plated layer was extremelyuniform.

Here, clogging occurred in the porous member, resulting in a particleloss of approximately 30%. After the plating test was repeated threetimes, clogging occurred too much, with the result that the porousmember was no longer usable.

EXAMPLE 6 (COMPARATIVE EXAMPLE)

Plating was carried out in the same manner as Example 5 except that theconventional manufacturing device for conductive fine particles shown inFIG. 2 was used, and that as illustrated in FIG. 8, a porous memberwhich was formed by affixing a nylon filter having a pore size of 10 μmonto the inner side surface on the treatment chamber side of a porousmember with a pore size of 70 μm that was formed from polypropylene, wasused as the porous member 12.

During the rotation of the treatment chamber, the plating solution,which was subjected to a force in the outer circumferential directiondue to the effect of a centrifugal force, formed a vortex having amortar-like shape and gradually rose along the inner wall of the cover1, with the result that the liquid was scattered from the opening 8 ofthe cover 1; consequently, the fine particles flowed (overflow) out ofthe treatment chamber together with the scattering plating solution, asa result failing to carry out plating.

However, after completion of the plating process, no clogging was foundin the porous member.

Here, this Example 6 should be described as a comparative example.

EXAMPLE 7

Solder plating was carried out on the surface in the same manner asExample 5, except that as illustrated in FIG. 8, a porous member, whichwas formed by affixing a nylon filter having a pore size of 10 μm ontothe inner side surface on the treatment chamber side of a porous memberwith a pore size of 70 μm that was formed from polypropylene, was usedas the porous member 12.

During the rotation of the treatment chamber, the plating solution,which was subjected to a force in the outer circumferential directiondue to the effect of a centrifugal force, formed a vortex having amortar-like shape; however, there was no overflowing from the upperopening of the hollow cover 1.

The solder plated resin fine particles having a solder plated layer asthe outermost layer thus obtained were observed under a microscope, andall the particles existed as individually isolated particles. Moreover,the average particle size of 100 of the solder plated resin fineparticles was 84.92 μl and the thickness of the solder plated layer was3.4 μm. The variation coefficient of the particle size was 3.1%, therebyindicating that the thickness of the solder plated layer was extremelyuniform.

Here, no clogging was found in the porous member 12, and even after theplating test had been repeated five times, no clogging was found.

EXAMPLE 8

A nickel plating layer is formed as a conductive base layer on each oforganic resin fine particles obtained by copolymerizing styrene anddivinylbenzene; thus, a nickel plating fine particle having an averageparticle size of 5.43 μm and a standard deviation of 0.16 μm wasobtained. The resulting nickel plating fine particles (2.5 g) weresubjected to nickel plating on their surface by using a manufacturingdevice for conductive fine particles shown in FIG. 1.

As illustrated in FIG. 8, a porous member, which was formed by affixinga nylon filter having a pore size of 3 μm onto the inner side surface onthe treatment chamber side of a porous member with a pore size of 70 μmthat was formed from polypropylene, was used as the porous member 12.Metal nickel was used as the anode 2 a. A Watt bath was used as theplating solution.

Power was applied across the electrodes with a voltage of 14 to 15 V for25 minutes, under the conditions that the temperature of the platingsolution was 50° C., the current was 30 A, and the current density was0.3 A/dm². The peripheral velocity of the treatment chamber was set at300 m/min, and the rotation direction was reversed every 11 seconds.

During the rotation of the treatment chamber, the plating solution,which was subjected to a force in the outer circumferential directiondue to the effect of a centrifugal force, formed a vortex having amortar-like shape; however, there was no overflowing from the upperopening of the hollow cover 1.

The nickel plated resin fine particles having a nickel plated layer asthe outermost layer thus obtained were observed under a microscope, andall the particles existed as individually isolated particles. Moreover,the average particle size of 100 of the nickel plated resin fineparticles was 7.23 μm and the thickness of the nickel plated layer was0.9 μm. The variation coefficient of the particle size was 2.8%, therebyindicating that the thickness of the nickel plated layer was extremelyuniform.

Moreover, no clogging was found in the porous member 12, and even afterthe repeated plating tests of five times, no clogging was found.

COMPARATIVE EXAMPLE 1

Plating was carried out in the same manner as Example 1 except that theconventional manufacturing device for conductive fine particles shown inFIG. 2 was used as the manufacturing device for conductive fineparticles, and that a porous member having a pore size of 20 μm, formedfrom high-density polyethylene, was used as the porous member 12.

During the rotation of the treatment chamber, the plating solution,which was subjected to a force in the outer circumferential directiondue to the effect of a centrifugal force, formed a vortex having amortar-like shape and gradually rose along the inner wall of the hollowcover 1, with the result that the liquid was scattered from the opening8 of the hollow cover 1; consequently, the fine particles flowed(overflow) out of the treatment chamber together with the scatteringplating solution, as a result failing to carry out plating. Moreover,clogging occurred in the porous member.

COMPARATIVE EXAMPLE 2

Plating was carried out in the same manner as Comparative Example 1except that the peripheral velocity was set to 250 m/min.

Even during the rotation of the treatment chamber, no overflowingoccurred; however, power was applied before the fine particles hadreached the contact ring, resulting in no adhesion of the platingmaterial.

COMPARATIVE EXAMPLE 3

Plating was carried out in the same manner as Example 4 by using theconventional manufacturing device for conductive fine particles shown inFIG. 2. Since the amount of the liquid in the treatment chamber wassmall, only the gross current amount of 26 A was allowed to flow with alow current density of 0.44 A/dm²; consequently, it took approximately70 minutes to complete all the plating in order to obtain the samethickness of nickel layer as Example 3. The plating time took about 1.5times as long.

COMPARATIVE EXAMPLE 4

Solder plating was carried out in the same manner as Example 5 exceptthat the conventional manufacturing device for conductive fine particlesshown in FIG. 2 was used as the manufacturing device for conductive fineparticles.

During the rotation of the treatment chamber, the plating solution,which was subjected to a force in the outer circumferential directiondue to the effect of a centrifugal force, formed a vortex having amortar-like shape and gradually rose along the inner wall of the hollowcover 1, with the result that the liquid was scattered from the opening8 of the hollow cover 1; consequently, the fine particles flowed(overflow) out of the treatment chamber together with the scatteringplating solution, as a result failing to carry out plating. Moreover,clogging occurred in the porous member.

COMPARATIVE EXAMPLE 5

Solder plating was carried out in the same manner as Example 8 exceptthat the conventional manufacturing device for conductive fine particlesshown in FIG. 2 was used as the manufacturing device for conductive fineparticles, and that a porous member having a pore size of 2 μm, formedof ceramics, was used as the porous member 12.

During the rotation of the treatment chamber, the plating solution,which was subjected to a force in the outer circumferential directiondue to the effect of a centrifugal force, formed a vortex having amortar-like shape and gradually rose along the inner wall of the hollowcover 1, with the result that the liquid was scattered from the opening8 of the hollow cover 1; consequently, the fine particles flowed(overflow) out of the treatment chamber together with the scatteringplating solution, as a result failing to carry out plating.

Table 2 shows the results of Examples 1 to 8 and Comparative Examples 1to 5. TABLE 1 Support Kinds of Particle Porous pore size Filter poreplating metal size (μm) Cover member Material (μm) size (μm) OverflowClogging Evaluation Example 1 Nickel 75 — PE 20 — none occurred ◯ 2Nickel 75 PP 70 10 occurred none Δ 3 Nickel 75 PP 70 10 none none ⊚ 4Nickel 250 — PP 70 — none none ⊚ 5 Solder 75 — PE 20 — none occurred ◯ 6Solder 75 PP 70 10 occurred none Δ 7 Solder 75 PP 70 10 none none ⊚ 8Nickel 5 PP 70 3 none none ⊚ Comparative 1 Nickel 75 — PE 20 — occurredoccurred X Example 2 Reduced number of rotations of Comparative Example1 none occurred X 3 Nickel 250 — PP 70 — none none Δ 4 Solder 75 — PE 20— occurred occurred X 5 Nickel 5 — Ceramics 2 — occurred occurred X

EXAMPLE 9

A nickel plating layer is formed as a conductive base layer on each oforganic resin fine particles having an average particle size of 93.45μm, a standard deviation of 1.30 μm and a variation coefficient of 1.4%,obtained by copolymerizing styrene and divinylbenzene; thus, a nickelplating fine particle having an average particle size of 97.10 μm, astandard deviation of 1.86 μm and a variation coefficient of 1.9% wasobtained. The resulting nickel plating fine particles (32.7 g) weresubjected to nickel plating on their surface by using a manufacturingdevice for conductive fine particles shown in FIG. 11.

A porous member, which was formed by affixing a nylon sheet-shapedfilter 20 having a pore size of 10 μm and a thickness of 10 μm onto theupper surface of a plate-shaped porous support 22 comprisinghigh-density polyethylene having a pore size of 100 μm and a thicknessof 6 mm, was used as the porous member 21. An alloy of tin (Sn):lead(Pb)=6:4 was used as the anode 2 a. Acid bath (537A) made by IshiharaChemical Co., Ltd. was used as the plating solution.

The composition of the plating solution was adjusted so that the totalmetal concentration was set in the range of 15 to 30 g/L, the metalratio in the bath, Sn %=55 to 65%, alkanol sulfonic acid, 100 to 150g/L, and an additive, 40 mL. The results of analysis on the platingsolution showed that the total metal concentration was 20 g/L, the metalratio in the bath, Sn %=65%, and alkanol sulfonic acid, 106 g/L.

Power was applied across the electrodes with a voltage of 10 to 12 V forthe total power application time of approximately 25 minutes, under theconditions that the temperature of the plating solution was 20° C., thecurrent was 50 A, and the current density was 0.5 A/dm². The peripheralvelocity of the treatment chamber was set at 226 m/min, and the rotationdirection was reversed every 7.5 seconds and total plating time wasabout 1 hour.

As a result, the application of the above-mentioned arrangement of theporous member solved the problem of the production of ring-shapedaggregated lumps due to pressed fine particles on the porous memberfiltering face during plating.

The nickel plated resin fine particles having an eutectic solder platedlayer as the outermost layer thus obtained were observed under amicroscope, and all the particles existed as individually isolatedparticles. Moreover, the average particle size of 100 of the solderplated resin fine particles was 103.78 μm and the thickness of thesolder plated layer was 3.34 μm. The variation coefficient of theparticle size was 2.8%, thereby indicating that the thickness of thesolder plated layer was extremely uniform. Moreover, no scratches werefound on the surface. The resulting solder coat was analyzed by theatomic absorption method, and Sn was 59.1%, which proved its eutecticcomposition.

In the following Examples and Comparative Examples, the evaluation itemsof the resulting conductive fine particles are given as (1) the ratio ofaggregated lumps (Table 2) and (2) the surface condition of particlesafter plating (Table 3). TABLE 2 Glade Degree of aggregation of platedparticles 0 none of aggregated lumps, each comprising not less than 5particles, in 1000 particles 1 1 to 10 of aggregated lumps, eachcomprising not less than 5 particles, in 1000 particles 2 11 to 30 ofaggregated lumps, each comprising not less than 5 particles, in 1000particles 3 31 to 50 of aggregated lumps, each comprising not less than5 particles, in 1000 particles 4 51 or more of aggregated lumps, eachcomprising not less than 5 particles, in 1000 particles

TABLE 3 Presence of separation marks and scratches on the surface Gladeof plated particles 0 none of particles having separation marks and/orscratches on the surface in 100 particles 1 1 to 3 particles havingseparation marks and/or scratches on the surface in 100 particles 2 4 to10 particles having separation marks and/or scratches on the surface in100 particles 3 11 to 20 particles having separation marks and/orscratches on the surface in 100 particles 4 21 or more of particleshaving separation marks and/or scratches on the surface in 100 particles

Moreover, from the results of observation on 100 particles undermicroscope, the average particle size and the thickness of the platinglayer were calculated.

EXAMPLE 10

A nickel layer was formed as a conductive base layer on each of organicresin fine particles obtained by copolymerizing styrene anddivinylbenzene; thus, nickel coated fine particles having an averageparticle size of 30.25 μm and a standard deviation of 1.13 μm wereobtained. The resulting nickel coated fine particles (7.5 g) weresubjected to nickel plating on their surface by using an electroplatingdevice shown in FIG. 1.

A nylon filter having a pore size of 10 μm was affixed onto the innerside surface on the treatment chamber side of a porous member that wasformed from polypropylene with a pore size of 70 μm; and this was usedas the porous member 12. Metal nickel was used as the anode 2 a. A Wattbath was used as the plating solution.

Power was applied across the electrodes with a voltage of 15 to 16 V for20 minutes, under the conditions that the temperature of the platingsolution was 50° C., the current was 36 A, and the current density was0.36 A/dm². The peripheral velocity of the treatment chamber was set at250 m/min, and the rotation direction was reversed every 11 seconds.

Nickel plated resin fine particles having a nickel plating layer ontheir outermost surface, thus obtained, were subjected to a pulverizingprocess under a pressure of 500 kg/cm² by using a high-pressurehomogenizer (made by Mizuho Kogyo K.K., Micro-fluidizer M-110Y).One-pass pulverizing process was carried out. FIG. 13 shows a systemflow diagram of the high-pressure homogenizer, and FIG. 14 shows a flowdiagram showing the inside of the chamber 18.

As illustrated in FIGS. 13 and 14, the material was supplied by a pump216, and a difference in pressures is occurred inside the chamber 218due to the correlation between the orifice diameter of the chamber 218and the supplying energy of the pump. This drop in pressure(cavitation), a shearing force due to the acceleration of the material,and an impact force exerted by the frontal collision of the acceleratedfluid were utilized for pulverizing the fine particles inside thechamber.

In this manner, conductive fine particles, each having a nickel platedlayer formed on its surface, were obtained.

EXAMPLE 11

In the same manner as Example 10 except that three passes of thepulverizing process were carried out, conductive fine particles, eachhaving a nickel plated layer formed on its surface, were obtained.

EXAMPLE 12

In the same manner as Example 10 except that five passes of thepulverizing process were carried out, conductive fine particles, eachhaving a nickel plated layer formed on its surface, were obtained.

EXAMPLE 13

The same plating process as Example 10 was carried out; however, duringthe plating process, the fine particles are drawn together with theplating solution continuously from the treatment chamber 13, and thiswas subjected to a pulverizing process by under a pressure of 500 kg/cm²by using a high-pressure homogenizer (made by Mizuho Kogyo K.K.,Micro-fluidizer M-110Y), and again returned to the treatment chamber 13;this operation was repeated until the completion of the plating process.

FIG. 15 shows a flow diagram showing a circulation system having thecombination of the electroplating device and the pulverizing device.

As illustrated in FIG. 15, a fine-particle drawing tube 221 was insertedfrom the upper opening of the treatment chamber (in which the tip of thedrawing tube is placed in the vicinity of the contact ring 11), and asuspension of the plating solution and the fine particles in thevicinity of the contact ring was sent to a container 214 by a platingfine-particle drawing pump 231. The suspension 215 of the platingsolution and the fine particles, sent to the container 214, was suppliedto the chamber 218 by a pump 216, and isolated into individual particlesby a pressure drop, a shearing force and an impact force, and thenreturned to the treatment chamber 13 by a pulverized fine-particlesupply tube 222.

Thus, conductive fine particles, each having a nickel plated layerformed on its surface, were obtained.

COMPARATIVE EXAMPLE 6

The same plating process as Example 10 was carried out so thatconductive fine particles, each having a nickel plated layer formed onits surface, were obtained; however, the pulverizing process wasomitted.

The results of Examples 10 to 13 and Comparative Example 6 are shown inTable 4. TABLE 4 Presence of Number of pulverizing Degree of separationprocess aggregation marks/scratches Ex. 10 1 pass Grade 2 Grade 2 Ex. 113 passes Grade 1 Grade 3 Ex. 12 5 passes Grade 0 Grade 4 Ex. 13Continuous pulverization Grade 0 Grade 0 Compar. none Grade 3 Grade 0Ex. 6

As shown in Table 4, when the pulverizing process was carried out aftercompletion of the plating (Example 10), the amount of aggregation wasreduced as compared with Comparative Example 6. However, separationmarks and scratches due to the pulverizing process were found on theplated surface. Moreover, the amount of aggregation reduced as thenumber of the pulverizing processes increased, and it became virtuallyzero after 5 passes; however, the amount of particles having separationmarks and scratches on their surface increased.

In the circulation system (Example 13) using the combination of theelectroplating device and the pulverizing device, the plating processand the pulverizing process are repeatedly carried out from the initialstage; therefore, aggregation hardly occurs, and it is possible to forma plating coat film without separation marks and scratches on thesurface of each particle.

EXAMPLE 14

A nickel layer was formed as a conductive base layer on each of organicresin fine particles obtained by copolymerizing styrene anddivinylbenzene; thus, nickel coated fine particles having an averageparticle size of 15.24 μm and a standard deviation of 0.70 μm wereobtained. The resulting nickel coated fine particles (10.0 g) weresubjected to nickel plating on their surface by using an electroplatingdevice shown in FIG. 1.

A nylon filter having a pore size of 10 μm was affixed onto the innerside surface on the treatment chamber side of a porous member with apore size of 70 μm that was formed from polypropylene; and this was usedas the porous member 12. Metal nickel was used as the anode. 2 a. A Wattbath was used as the plating solution.

Power was applied across the electrodes with a voltage of 15 to 16 V for20 minutes, under the conditions that the temperature of the platingsolution was 50, the current was 36 A, and the current density was 0.36A/dm². The peripheral velocity of the treatment chamber was set at 250m/min, and the rotation direction was reversed every 11 seconds.

During the plating process, the fine particles were drawn together withthe plating solution continuously from the treatment chamber 13, andthis was subjected to a pulverizing process by a homomixer (made byTokushukika Kogyo K.K., T.K. Pipeline Homomixer PL-SL) at 5000 rpm, andagain returned to the treatment chamber 13; this operation was repeateduntil the completion of the plating process.

FIG. 16 shows a flow diagram showing such a circulation system havingthe combination of the electroplating device and the pulverizing device.

As illustrated in FIG. 16, a fine-particle drawing tube 221 was insertedfrom the upper opening of the treatment chamber (in which the tip of thedrawing tube is placed in the vicinity of the contact ring 11), and asuspension of the plating solution and the fine particles in thevicinity of the contact ring was drawn, and subjected to a pulverizingprocess by a Pipeline Homomixer 225, and then returned to the treatmentchamber 13 by a pulverized fine-particle supply tube 222.

Thus, conductive fine particles, each having a nickel plated layerformed on its surface, were obtained.

COMPARATIVE EXAMPLE 7

The same plating process as Example 14 was carried out so thatconductive fine particles, each having a nickel plated layer formed onits surface, were obtained; however, the pulverizing process wasomitted.

The results of Examples 14 and Comparative Example 7 are shown in Table5. TABLE 5 Presence of Number of pulverizing Degree of separationprocess aggregation marks/scratches Ex. 14 Continuous pulverizationGrade 0 Grade 1 Compar. none Grade 3 Grade 0 Ex. 7

EXAMPLE 15

A nickel layer was formed as a conductive base layer on each of organicresin fine particles obtained by copolymerizing styrene anddivinylbenzene; thus, nickel coated fine particles having an averageparticle size of 6.74 μm and a standard deviation of 0.40 μm wereobtained. The fine particles obtained were subjected to nickelelectroplating in the same manner as Example 5 so that nickel platedfine particles having an average particle size of 8.82 μm and a nickelplating thickness of 1.04 μm were obtained. These nickel plated fineparticles were subjected to solder plating on their surface by using anelectroplating device shown in FIG. 1.

A nylon filter having a pore size of 5 μm was affixed onto the innerside surface on the treatment chamber side of a porous member with apore size of 70 μm that was formed from polypropylene; and this was usedas the porous member 12. Metal nickel was used as the anode 2 a. Analkane sulfonic acid solder bath was used as the plating solution. Thecomposition of the bath was: tin(I)alkanesulfonate 60 ml/L, lead alkanesulfonate 30 ml/L, radical alkane sulfonic acid 100 ml/L and brightener80 ml/L.

Power was applied across the electrodes with a voltage of 16 to 17 V for15 minutes, under the conditions that the temperature of the platingsolution was 20° C., the current was 80.6 A, and the current density was0.75 A/dm². The peripheral velocity of the treatment chamber was set at250 m/min, and the rotation direction was reversed every 15 seconds.

During the plating process, the fine particles were drawn together withthe plating solution continuously from the treatment chamber 13, andthis was subjected to a pulverizing process by a static mixer (productsby Tokushukika Kogyo K.K., T.K.—ROSS ISG mixer), and again returned tothe treatment chamber 13; this operation was repeated until thecompletion of the plating process.

FIG. 17 shows a flow diagram showing such a circulation system havingthe combination of the electroplating device and the pulverizing device.

As illustrated in FIG. 17, a fine-particle drawing tube 221 was insertedfrom the upper opening of the treatment chamber (in which the tip of thedrawing tube is placed in the vicinity of the contact ring 11), and asuspension of the plating solution and the fine particles in thevicinity of the contact ring was drawn, and subjected to a pulverizingprocess by a static mixer 226, and then returned to the treatmentchamber 13 by a pulverized fine-particle supply tube 222.

Thus, conductive fine particles, each having a solder plated layerformed on its surface, were obtained.

COMPARATIVE EXAMPLE 8

The same plating process as Example 6 was carried out so that conductivefine particles, each having a nickel plated layer formed on its surface,were obtained; however, the pulverizing process was omitted.

The results of Examples 15 and Comparative Example 8 are shown in Table6. TABLE 6 Presence of Number of pulverizing Degree of separationprocess aggregation marks/scratches Ex. 15 Continuous pulverizationGrade 0 Grade 1 Compar. none Grade 4 Grade 0 Ex. 8

EXAMPLE 16

A nickel layer was formed as a conductive base layer on each of organicresin fine particles obtained by copolymerizing styrene anddivinylbenzene; thus, nickel coated fine particles having an averageparticle size of 2.98 μm and a standard deviation of 0.22 μm wereobtained. The resulting nickel coated fine particles (8.0 g) weresubjected to nickel plating on their surface by using an electroplatingdevice shown in FIG. 1.

A membrane filter having a pore size of 10 μm was affixed onto the innerside surface on the treatment chamber side of a porous member with apore size of 70 μm that was formed from polypropylene; and this was usedas the porous member 12. The membrane filter has a collecting efficiencyof 98% with respect to 2 μm particles and a collecting efficiency of notless than 99.9% with respect to 3 μm particles. Metal nickel was used asthe anode 2 a. A Watt bath was used as the plating solution.

Power was applied across the electrodes with a voltage of 16 to 17 V for50 minutes, under the conditions that the temperature of the platingsolution was 50° C., the current was 36 A, and the current density was0.20 A/dm². The peripheral velocity of the treatment chamber was set at250 m/min, and the rotation direction was reversed every 15 seconds.

During the plating process, the fine particles were drawn together withthe plating solution continuously from the treatment chamber 13, andthis was subjected to a pulverizing process by an ultrasonic generator(products by Tsutsui Rikagakukikaisha K.K. Ultrasonic washer AU-70C) ata frequency of 28 kHz/s, and then again returned to the treatmentchamber 13; this operation was repeated until the completion of theplating process.

FIG. 18 shows a flow diagram showing such a circulation system havingthe combination of the electroplating device and the pulverizing device.

As illustrated in FIG. 18, a fine-particle drawing tube 221 was insertedfrom the upper opening of the treatment chamber (in which the tip of thedrawing tube is placed in the vicinity of the contact ring 11), and asuspension of the plating solution and the fine particles in thevicinity of the contact ring was drawn by a plated fine-particle drawingpump 231, and sent to a glass container 229. The suspension of theplating solution and the fine particles, sent to the glass container229, was isolated into individual particles by the pulverizing effect ofultrasonic waves exerted by the ultrasonic generator 227, and thenreturned to the treatment chamber 13 by a pulverized fine-particlesending pump 230 through a pulverized fine-particle supply tube 222.

Thus, conductive fine particles, each having a nickel plated layerformed on its surface, were obtained.

COMPARATIVE EXAMPLE 9

The same plating process as Example 16 was carried out so thatconductive fine particles, each having a nickel plated layer formed onits surface, were obtained; however, the pulverizing process wasomitted. The results of Examples 16 and Comparative Example 9 are shownin Table 7. TABLE 7 Presence of Number of pulverizing Degree ofseparation process aggregation marks/scratches Ex. 16 Continuouspulverization Grade 1 Grade 0 Compar. none Grade 4 Grade 0 Ex. 9

EXAMPLE 17

A nickel plating layer was formed as a conductive base layer by anelectroless plating method on each of organic resin fine particleshaving a specific gravity of 1.19, an average particle size of 98.76 μm,a standard deviation of 1.48 and a variation coefficient of 1.5%,obtained by copolymerizing styrene and divinylbenzene; thus, electrolessnickel plated fine particles having an electroless nickel-film thicknessof 2000 Å were obtained.

The resulting electroless nickel plated fine particles (20.0 g) weresubjected to nickel plating on their surface by using a manufacturingdevice for conductive fine particles of the present invention 11 shownin FIG. 19.

With respect to the treatment chamber 315, a partition plate 314 whichwas formed by affixing a nylon filter sheet having a pore size of 10 μmand a thickness of 10 μm onto the inner side surface of a resin (HT-PVC)plate having a number of pores (φ5) was used to form it; thus, fineparticles into the treatment chamber 315 were prevented from leakinginto the plating vessel 313.

The treatment chamber 315 was designed to have a particle shiftingdistance A of 40 mm into the treatment chamber 315.

A ring-shaped porous member having a pore size of 100 μm and a thicknessof 6 mm, made from high-density polyethylene, was used as the porousmember 12. Metal nickel was used as the anode 2 a.

A Watt bath was used as the plating solution. The composition of theplating solution was: nickel concentration 42 g/L, nickel chloride 39g/L, nickel sulfate 150 g/L, and boric acid 31 g/L. The plating solutionhas a pH of 3.8 and a specific gravity of 1.11.

Power was applied across the electrodes under the conditions that thetemperature of the plating solution was 50° C., the current was 34 A,and the current density was 0.37 A/dm². The driving condition was set sothat the number of revolutions of the plating vessel 13 provides acentrifugal effect of 10.3. The plating vessel 13 used here had an innerdiameter of 280 mm, the number of revolutions was 256.5 rpm, and theperipheral velocity of the inner side surface of the contact ring 11 was225.6 m/min. The particle shifting time was 2 seconds, the powerapplication time was 5 seconds, the deceleration time was 1 second, andthe stoppage time was 1 second; thus, with the total 9 seconds as onecycle, the forward rotation and the reverse rotation were repeated. Inthis case, the power application rate (the ratio of the powerapplication time in one cycle) was 55.6%. The total plating time wasapproximately 72 minutes.

The nickel plated resin fine particles having a nickel plated layer asthe outermost layer thus obtained were observed under an opticalmicroscope, and all the particles existed as individually isolatedparticles without any aggregation. Moreover, the average particle sizeof 300 of the nickel plated resin fine particles was 103.40 μm and thethickness of the nickel plated layer was 2.12 μm. The variationcoefficient of the particle size was 2.7%, thereby indicating that thethickness of the nickel plated layer was extremely uniform. Moreover,there were no particles influenced by a melt down base nickel platinglayer due to the bipolar phenomenon.

EXAMPLE 18

Nickel plating was carried out in the same manner as Example 17 by usingthe electroless nickel plating fine particles used in Example 17, exceptthat one cycle was set to 8 seconds including the particle shifting timeof 2 seconds, the power application time of 5 seconds, the decelerationtime of 1 second and the stoppage time of 0 second. In this case, thepower application rate (the ratio of the power application time in onecycle) was 62.5%. The total plating time was approximately 64 minutes.

The nickel plated resin fine particles having a nickel plated layer asthe outermost layer thus obtained were observed under an opticalmicroscope, and all the particles existed as individually isolatedparticles without any aggregation. Moreover, the average particle sizeof 300 of the nickel plated resin fine particles was 103.26 μm and thethickness of the nickel plated layer was 2.05 μm. The variationcoefficient of the particle size was 2.9%, thereby indicating that thethickness of the nickel plated layer was extremely uniform. Moreover,there were no particles influenced by a melt down base nickel platinglayer due to the bipolar phenomenon.

EXAMPLE 19

By using the electroless nickel plating fine particles used in Example17, nickel plating was carried out in the same manner as Example 17except the following factors:

The treatment chamber 315 was formed so as to set the particle shiftingdistance A inside the treatment chamber at 15 mm, and

as for the driving conditions, one cycle was set to 7 seconds includingthe particle shifting time of 1 second, the power application time of 5seconds, the deceleration time of 1 second and the stoppage time of 0second. In this case, the power application rate (the ratio of the powerapplication time in one cycle) was 71.4%. The total plating time wasapproximately 56 minutes.

The nickel plated resin fine particles having a nickel plated layer asthe outermost layer thus obtained were observed under an opticalmicroscope, and all the particles existed as individually isolatedparticles without any aggregation. Moreover, the average particle sizeof 300 of the nickel plated resin fine particles was 103.34 μm and thethickness of the nickel plated layer was 2.09 μm. The variationcoefficient of the particle size was 2.8%, thereby indicating that thethickness of the nickel plated layer was extremely uniform. Moreover,there were no particles influenced by a melt down base nickel platinglayer due to the bipolar phenomenon.

COMPARATIVE EXAMPLE 9

Nickel plating was carried out in the same manner as Example 17 exceptthat 20 g of the electroless nickel plating fine particles used inExample 17 was used, and that a conventional manufacturing device forconductive fine particles shown in FIG. 20 was used.

In the case of the conventional manufacturing device for conductive fineparticles, since the particle shifting distance was too long, powerapplication was started before the fine particles had reached thecontact ring, with the result that the bipolar phenomenon occurred,causing melt-down in the electroless plating layers of not less thanhalf the number of fine particles, as a result failing to carry outplating.

EXAMPLE 20

A nickel plating layer was formed as a conductive base layer on each oforganic resin fine particles having an average particle size of 203.18μm, a standard deviation of 3.05, and a variation coefficient 1.5%,obtained by copolymerizing styrene and divinylbenzene; thus, nickelcoated fine particles having an average particle size of 208.29 μm, astandard deviation of 4.58 and a variation coefficient of 2.2% wereobtained (with a nickel film thickness of approximately 2.5 μm). Theresulting nickel plated fine particles (30.0 g) were subjected toeutectic solder plating on their surface by using a manufacturing devicefor conductive fine particles shown in FIG. 11.

A porous member, which was formed by affixing a nylon filter sheet 20having a pore size of 10 μm and a thickness of 10 m onto the uppersurface of a plate-shaped porous support 12 having a pore size of 100 μmand a thickness of 6 mm, made from high density polyethylene, was usedas the porous member 21.

An alloy of tin (Sn):lead (Pb)=6:4 was used as the anode 2 a.

Acid bath (537A) (made by Ishihara Chemical Co., Ltd.) was used as theplating solution.

The composition of the plating solution was adjusted so that the totalmetal concentration was 21.39 g/L, the metal ratio in the bath, Sn % was65.3%, alkanol sulfonic acid was 106.4 g/L, and an additive was 40 mL.

Power was applied across the electrodes under the conditions that thetemperature of the plating solution was 20° C., the current was 24.8 A,and the current density was 0.5 A/dm².

The driving condition was set so that the number of revolutions of thetreatment chamber 13 provides a centrifugal effect of 10.3. Thetreatment chamber 13 used here had an inner diameter of 280 mm, thenumber of revolutions of the treatment chamber was 256.5 rpm, and theperipheral velocity thereof was 225.6 m/min. The driving pattern of thepower application process was set so that one cycle included theparticle shifting time of 2 seconds, the power application time of 6seconds, the deceleration time of 0.5 second, and the stoppage time of 2seconds, and the driving pattern of the stirring process was set so thatone cycle included the rotation time of 1 second, the deceleration timeof 0.5 second, and the stoppage time of 1 second; thus, the powerapplication process and the stirring process were carried outalternately. The total plating time was approximately 83 minutes.

FIG. 21 shows a time chart of the driving conditions.

The eutectic solder plated resin fine particles having an eutecticsolder plated layer as the outermost layer thus obtained were observedunder an optical microscope, and all the particles existed asindividually isolated particles.

Moreover, the average particle size of 300 of the eutectic solder platedresin fine particles was 219.47 μm and the thickness of the solderplated layer was 5.59 μm. The variation coefficient of the particle sizewas 3.1%, thereby indicating that the thickness of the solder platedlayer was extremely uniform. Moreover, no scratches were found on thesurface.

The resulting solder coat was analyzed by the atomic absorption method,and Sn was 61.3%, which proved its eutectic composition.

EXAMPLE 21

Eutectic solder plating was carried out in the same manner as Example 20by using the same nickel plating fine particles (average particle size:208.29 μm, a standard deviation: 4.58, variation coefficient: 2.2% andnickel film thickness: approximately 2.5 μm) as Example 20, except thatthe driving conditions were altered as follows:

The current value was set to 74.5 A, and the current density was set to1.5 A/dm²; thus, the plating was carried out.

The driving condition was set so that the number of revolutions of thetreatment chamber provides a centrifugal effect of 10.3. The treatmentchamber used here had an inner diameter of 280 mm, the number ofrevolutions of the treatment chamber was 256.5 rpm, and the peripheralvelocity thereof was 225.6 m/min. The driving pattern of the powerapplication process was set so that one cycle included the particleshifting time of 2 seconds, the power application time of 6 seconds, thedeceleration time of 0.5 second, and the stoppage time of 2 seconds, andthe driving pattern of the stirring process was set so that one cycleincluded the rotation time of 1 second, the deceleration time of 0.5seconds, and the stoppage time of 1 second. The plating was carried outat the ratio of one cycle of the power application process to fourcycles of the stirring processes, with the respective power-applicationprocess and the stirring process being repeated alternately in theirforward and reverse rotations. The total plating time was approximately49 minutes.

FIG. 22 shows a time chart of the driving conditions. The eutecticsolder plated resin fine particles having an eutectic solder platedlayer as the outermost layer thus obtained were observed under anoptical microscope, and all the particles existed as individuallyisolated particles.

Moreover, the average particle size of 300 of the eutectic solder platedresin fine particles was 219.43 μm and the thickness of the solderplated layer was 5.57 μm. The variation coefficient of the particle sizewas 3.3%, thereby indicating that the thickness of the solder platedlayer was extremely uniform.

The resulting solder coat was analyzed by the atomic absorption method,and Sn was 62.8%, which proved its eutectic composition.

COMPARATIVE EXAMPLE 10

Eutectic solder plating was carried out in the same manner as Example 20by using the same nickel plating fine particles (average particle size:208.29 μl, a standard deviation: 4.58, variation coefficient: 2.2% andnickel film thickness: approximately 2.5 μm), except that the drivingconditions were altered as follows:

The current value was set to 24.8 A, and the current density was set to0.5 A/dm²; thus, the plating was carried out.

The driving condition was set so that the number of revolutions of thetreatment chamber provides a centrifugal effect of 10.3. The treatmentchamber used here had an inner diameter of 280 mm, the number ofrevolutions of the treatment chamber was 256.5 rpm, and the peripheralvelocity thereof was 225.6 m/min. The driving pattern of the powerapplication process was set so that one cycle included the particleshifting time of 2 seconds, the power application time of 6 seconds, thedeceleration time of 0.5 second, and the stoppage time of 2 seconds, andno stirring process was applied; thus, the plating was carried out byrepeating forward and reverse rotations during only the powerapplication process. The total plating time was approximately 62minutes.

FIG. 23 shows a time chart of the driving conditions.

The eutectic solder plated resin fine particles having an eutecticsolder plated layer as the outermost layer thus obtained were observedunder an optical microscope, and a number of aggregated lumps, eachformed by approximately 3 to 10 particles, were found. Thus, it wasshown that aggregated lumps are formed in the case when no stirringprocess is applied while using the same power application time asExample 20.

COMPARATIVE EXAMPLE 11

Eutectic solder plating was carried out in the same manner as Example 20by using the same nickel plating fine particles (average particle size:208.29 μm, a standard deviation: 4.58, variation coefficient: 2.2% andnickel film thickness: approximately 2.5 μm), except that the drivingconditions were altered as follows:

The current value was set to 74.5 A, and the current density was set to1.5 A/dm²; thus, the plating was carried out.

The driving condition was set so that the number of revolutions of thetreatment chamber provides a centrifugal effect of 10.3. The treatmentchamber used here had an inner diameter of 280 mm, the number ofrevolutions of the treatment chamber was 256.5 rpm, and the peripheralvelocity thereof was 225.6 m/min. The driving pattern of the powerapplication process was set so that one cycle included the particleshifting time of 2 seconds, the power application time of 3 seconds, thedeceleration time of 0.5 second, and the stoppage time of 2 seconds, andno stirring process was applied; thus, the plating was carried out byrepeating forward and reverse rotations during only the powerapplication process. The total plating time was approximately 62minutes.

FIG. 24 shows a time chart of the driving conditions.

The eutectic solder plated resin fine particles having an eutecticsolder plated layer as the outermost layer thus obtained were observedunder an optical microscope, and a number of aggregated lumps, eachformed by approximately 5 to 15 particles, were found. Thus, it wasshown that aggregated lumps are formed in the case when no stirringprocess is applied with an increased current density.

Table 8 shows the results of Examples 20 and 21 as well as ComparativeExamples 10 and 11. TABLE 8 Driving pattern (sec.) Power applicationTotal Current process Stirring process plating density Power Deceler-Deceler- Number of time Presence of Total (A/dm²) shift applicationation Stoppage Rotation ation Stoppage repetitions (min.) aggregationevaluation Ex. 20 0.5 2 6 0.5 2 2 0.5 1 1 83 none ◯ Ex. 21 1.5 2 6 0.5 22 0.5 1 4 49 none ⊚ Comper. 0.5 2 6 0.5 2 — — — — 62 occurred X Ex. 10Comper. 1.5 2 3 0.5 2 — — — — 30 occurred X Ex. 11

EXAMPLE 22

A nickel plating layer was formed as a conductive base layer by anelectroless plating method on each of organic resin fine particleshaving a specific gravity of 1.19, an average particle size of 656.38μm, a standard deviation of 9.75 μm and a variation coefficient of 1.5%,obtained by copolymerizing styrene and divinylbenzene; thus, electrolessnickel plated fine particles having an electroless nickel-film thicknessof 5000 Å were obtained. The specific gravity of the electroless nickelplated fine particles thus obtained was 1.225.

The resulting nickel plated fine particles (105 g) were subjected tonickel plating on their surface by using a manufacturing device forconductive fine particles shown in FIG. 1.

A porous member, which was formed by affixing a nylon filter sheethaving a pore size of 10 μm and a thickness of 10 μm onto the uppersurface of a plate-shaped porous support having a pore size of 100 μmand a thickness of 6 mm, made from high density polyethylene, was usedas the porous member 12.

Metal nickel was used as the anode 2 a.

A Watt bath was used as the plating solution. The composition of theplating solution was 68 g/L of nickel concentration, 42 g/L of nickelchloride, 260 g/L of nickel sulfate, and 42 g/L of boric acid. Theplating solution had a pH of 3.7 and a specific gravity of 1.18.

Power was applied across the electrodes under the conditions that thetemperature of the plating solution was 50° C., the current was 32 A,and the current density was 0.4 A/dm². Here, the total power applicationtime was approximately 80 minutes. The peripheral velocity of thetreatment chamber was 226 m/min, and the rotation direction was reversedevery 11 seconds.

By increasing the film thickness of the electroless plating as describedabove, the difference between it and the bath specific gravity waswidened to not less than 0.04 so that all the fine particles wereallowed to completely approach the contact ring, thereby as a resultfailing to form a uniform plating layer.

The nickel plated resin fine particles having a nickel plated layer asthe outermost layer thus obtained were observed under an opticalmicroscope, and all the particles existed as individually isolatedparticles without any aggregation. From cross-sectional photographs ofthe resulting nickel plated resin fine particles, it was confirmed thatplating was uniformly formed on the surface of each particle. Moreover,the average particle size of 300 of the nickel plated resin fineparticles was 661.18 μm and the thickness of the nickel plated layer was5.40 μm. The variation coefficient of the particle size was 2.7%,thereby indicating that the thickness of the nickel plated layer wasextremely uniform. Moreover, there were no particles influenced by amelt down base nickel plating layer due to the bipolar phenomenon.

EXAMPLE 23

A nickel layer was formed as a conductive base layer by an electrolessplating method on each of organic resin fine particles same as thoseused in Example 22; thus, electroless nickel plated fine particleshaving an electroless nickel-film thickness of 2000 Å were obtained. Thespecific gravity of the electroless nickel plated fine particles thusobtained was 1.204.

The resulting nickel plated fine particles (105 g) were subjected tonickel plating on their surface by using a manufacturing device forconductive fine particles shown in FIG. 1.

The nickel plating was carried out in the same manner as Example 1,except that the composition of a Watt bath used here was altered asfollows: nickel concentration was 42 g/L, nickel chloride was 39 g/L,nickel sulfate was 150 g/L, and boric acid was 31 g/L. The platingsolution had a pH of 3.8 and a specific gravity of 1.11.

Even in the case when the film thickness of the electroless plating wasthinner than that of Example 22 and the particle specific gravity wassmall, the difference between it and the bath specific gravity wasincreased to not less than 0.04 by reducing the electrolyticconcentration of the Watt bath as described above, so that all the fineparticles were allowed to completely approach the contact ring, therebyforming a uniform plating layer.

The nickel plated resin fine particles having a nickel plated layer asthe outermost layer thus obtained were observed under an opticalmicroscope, and all the particles existed as individually isolatedparticles without any aggregation. From cross-sectional photographs ofthe resulting nickel plated resin fine particles, it was confirmed thatplating was uniformly formed on the surface of each particle. Moreover,the average particle size of 300 of the nickel plated resin fineparticles was 660.72 μm and the thickness of the nickel plated layer was5.170 μm. The variation coefficient of the particle size was 2.7%,thereby indicating that the thickness of the nickel plated layer wasextremely uniform. Moreover, there were no particles influenced by amelt down base nickel plating layer due to the bipolar phenomenon.

EXAMPLE 24

A nickel layer was formed as a conductive base layer by an electrolessplating method on each of glass beads having a specific gravity of 2.54,an average particle size of 203.67 μm, a standard deviation of 4.10 μmand a variation coefficient of 2.0%; thus, electroless nickel platedfine particles having a nickel-film thickness of 600 Å were obtained.The specific gravity of the electroless nickel plated fine particlesthus obtained was 2.551.

The resulting nickel plated fine particles (75 g) were subjected tonickel plating on their surface by using a manufacturing device forconductive fine particles shown in FIG. 1.

A porous member, which was formed by affixing a nylon filter sheethaving a pore size of 10 μm and a thickness of 10 μm onto the uppersurface of a plate-shaped porous support having a pore size of 100 μmand a thickness of 6 mm, made from high density polyethylene, was usedas the porous member 12.

Metal nickel was used as the anode 2 a.

A Watt bath was used as the plating solution. The composition of theplating solution was 45 g/L of nickel chloride, 300 g/L of nickelsulfate, and 45 g/L of boric acid. The plating solution had a pH of 3.7and a specific gravity of 1.23.

Power was applied across the electrodes under the conditions that thetemperature of the plating solution was 50° C., the current was 40 A,and the current density was 0.90 A/dm². Here, the total powerapplication time was approximately 35 minutes. The peripheral velocityof the treatment chamber was 226 m/min, and the rotation direction wasreversed every 11 seconds.

As described above, by setting the difference between its specificgravity and the bath specific gravity to 1.321 so that all the fineparticles were allowed to completely approach the contact ring, therebyforming a uniform plating layer.

The nickel plated glass beads having a nickel plated layer as theoutermost layer thus obtained were observed under an optical microscope,and all the particles existed as individually isolated particles withoutany aggregation. From cross-sectional photographs of the resultingnickel plated glass beads, it was confirmed that plating was uniformlyformed on the surfac of each particle. Moreover, the average particlesize of 300 of the nickel plated glass beads was 210.13 μm and thethickness of the nickel plated layer was 3.23 μm. The variationcoefficient of the particle size was 3.7%, thereby indicating that thethickness of the nickel plated layer was extremely uniform. Moreover,there were no particles influenced by a melt down base nickel platinglayer due to the bipolar phenomenon.

EXAMPLE 25

Copper fine particles (200 g) having a specific gravity of 8.93, anaverage particle size of 301.45 μm, a standard deviation of 4.67 μm anda variation coefficient of 1.5% were subjected to nickel plating ontheir surface.

A porous member, which was formed by affixing a nylon filter sheethaving a pore size of 10 μm and a thickness of 10 μm onto the uppersurface of a plate-shaped porous support having a pore size of 100 μmand a thickness of 6 mm, made from high density polyethylene, was usedas the porous member 12.

Metal nickel was used as the anode 2 a.

A Watt bath was used as the plating solution. The composition of theplating solution was 45 g/L of nickel chloride, 300 g/L of nickelsulfate, and 45 g/L of boric acid. The plating solution had a pH of 3.7and a specific gravity of 1.23.

Power was applied across the electrodes under the conditions that thetemperature of the plating solution was 50° C., the current was 40 A,and the current density was 0.90 A/dm². Here, the total powerapplication time was approximately 35 minutes. The peripheral velocityof the treatment chamber was 226 m/min, and the rotation direction wasreversed every 11 seconds.

As described above, by setting the difference between its specificgravity and the bath specific gravity to 7.7 so that all the fineparticles were allowed to completely approach the contact ring, therebyforming a uniform plating layer.

The nickel plated copper fine particles having a nickel plated layer asthe outermost layer thus obtained were observed under an opticalmicroscope, and all the particles existed as individually isolatedparticles without any aggregation. From cross-sectional photographs ofthe resulting nickel plated copper fine particles, it was confirmed thatplating was uniformly formed on the surfac of each particle. Moreover,the average particle size of 300 of the nickel plated copper fineparticles was 310.38 μm and the thickness of the nickel plated layer was4.46 μm. The variation coefficient of the particle size was 2.8%,thereby indicating that the thickness of the nickel plated layer wasextremely uniform. Moreover, there were no particles influenced by amelt down base nickel plating layer due to the bipolar phenomenon.

EXAMPLE 26

Lead fine particles (200 g) having a specific gravity of 11.34, anaverage particle size of 448.76 μm, a standard deviation of 7.63 μm anda variation coefficient of 1.7% were subjected to nickel plating ontheir surface by using a manufacturing device for conductive fineparticles shown in FIG. 1.

A porous member, which was formed by affixing a nylon filter sheethaving a pore size of 10 μm and a thickness of 10 μm onto the uppersurface of a plate-shaped porous support having a pore size of 100 μmand a thickness of 6 mm, made from high density polyethylene, was usedas the porous member 12.

Metal nickel was used as the anode 2 a.

A Watt bath was used as the plating solution. The composition of theplating solution was 45 g/L of nickel chloride, 300 g/L of nickelsulfate, and 45 g/L of boric acid. The plating solution had a pH of 3.7and a specific gravity of 1.23.

Power was applied across the electrodes under the conditions that thetemperature of the plating solution was 5° C., the current was 23.5 A,and the current density was 1.0 A/dm². Here, the total power applicationtime was approximately 30 minutes. The peripheral velocity of thetreatment chamber was 226 m/min, and the rotation direction was reversedevery 11 seconds.

As described above, by setting the difference between its specificgravity and the bath specific gravity to 10.11 so that all the fineparticles were allowed to completely approach the contact ring, therebyforming a uniform plating layer.

The nickel plated lead fine particles having a nickel plated layer asthe outermost layer thus obtained were observed under an opticalmicroscope, and all the particles existed as individually isolatedparticles without any aggregation. From cross-sectional photographs ofthe resulting nickel plated lead fine particles, it was confirmed thatplating was uniformly formed on the surface of each particle. Moreover,the average particle size of 300 of the nickel plated lead fineparticles was 459.26 μm and the thickness of the nickel plated layer was5.25 μm. The variation coefficient of the particle size was 3.1%,thereby indicating that the thickness of the nickel plated layer wasextremely uniform. Moreover, there were no particles influenced by amelt-down base nickel plating layer due to the bipolar phenomenon.

COMPARATIVE EXAMPLE 12

Nickel plating was carried out on the surface of the completely sameelectroless nickel plated fine particles (plating solution specificgravity: 1.204) as Example 23 by using a manufacturing device forconductive fine particles shown in FIG. 1 under the completely sameplating conditions (specific gravity: 1.18) as Example 1.

Since the difference in specific gravity between the plated fineparticles and the plating solution was as small as 0.024, powerapplication was started before the fine particles had reached contactring, with the result that there were a number of fine particles havingmelt-down conductive base layers due to the bipolar phenomenon.

COMPARATIVE EXAMPLE 13

A nickel plating layer was formed as a conductive base layer on each ofthe completely same organic resin fine particles as Example 22 by usingan electroless plating method; thus, electroless nickel plated fineparticles having an electroless nickel film thickness of 600 Å wereobtained. The resulting electroless nickel plating fine particles had aspecific gravity of 1.194.

The nickel plated fine particles (105 g) thus obtained were subjected toplating on their surface by using a manufacturing device for conductivefine particles shown in FIG. 1 under the completely same platingconditions (plating solution specific gravity: 1.18) as Example 1.

Since the difference in specific gravity between the plated fineparticles and the plating solution was 0.014, which was far smaller thanthat of Comparative Example 1, power application was started beforealmost all the fine particles had reached contact ring, with the resultthat almost all the fine particles were subjected to melt downconductive base layers due to the bipolar phenomenon.

Table 9 shows the results of Examples 22 to 26 and Comparative Examples12 and 13. Here, with respect to the evaluation in Table 9, theoccurrence of malplating due to the bipolar phenomenon was evaluatedbased upon the following criteria.

-   ◯: not observed-   X: malplating in not less than half

XX: malplating in almost all TABLE 9 Electroless Particle BathDifference Particle Particle Plating film specific specific in specificmaterial size (μm) thickness (Å) gravity gravity gravity Evaluation Ex.22 Organic resin 650.38 5000 1.225 1.18 0.045 ◯ Ex. 23 Organic resin650.38 2000 1.204 1.11 0.094 ◯ Ex. 24 Glass 203.67 600 2.551 1.23 1.321◯ Ex. 25 Copper 301.45 — 8.93 1.23 7.7 ◯ Ex. 26 Lead 448.76 — 11.34 1.2310.11 ◯ Comper. Ex. 12 Organic resin 650.38 2000 1.204 1.18 0.024 XComper. Ex. 13 Organic resin 650.38 600 1.194 1.18 0.014 X X

EXAMPLE 27

A nickel plated layer was formed as a conductive base layer by anelectroless plating method on each of organic resin fine particleshaving a specific gravity of 1.19, an average particle size of 650.8 μm,a standard deviation of 9.75 μm and a variation coefficient of 1.5%,formed by copolymerizing styrene and divinylbenzene; thus, electrolessnickel plated fine particles having an ectrololess nickel-film thicknessof 2000 Å were obtained. The specific gravity of the electroless nickelplated fine particles thus obtained was 1.204.

The resulting nickel plated fine particles (105 g) were subjected tonickel plating on their surface by using a manufacturing device forconductive fine particles shown in FIG. 11.

A porous member, which was formed by affixing a nylon filter sheet 20having a pore size of 10 μm and a thickness of 10 μm onto the uppersurface of a plate-shaped porous support 22 having a pore size of 100 μmand a thickness of 6 mm, made from high density polyethylene, was usedas the porous member 21.

Metal nickel was used as the anode 2 a.

A Watt bath was used as the plating solution.

The composition of the plating solution was 42 g/L of nickelconcentration, 39 g/L of nickel chloride, 150 g/L of nickel sulfate, and31 g/L of boric acid. The plating solution had a pH of 3.8 and aspecific gravity of 1.11.

Power was applied across the electrodes under the conditions that thetemperature of the plating solution was 50° C., the current was 32 A,and the current density was 0.4 A/dm². Here, the total power applicationtime was approximately 80 minutes.

With respect to the driving conditions, the number of revolutions of thetreatment chamber was set so as to provide a centrifugal effect of 10.3.The inner diameter of the treatment chamber used in this case was 280mm, and the number of revolutions of the treatment chamber was 256.5rpm, and the peripheral velocity thereof was 225.6 m/min. The particleshifting time was 4 seconds, the power application time was 5 seconds,the deceleration time was 1 second, and the stoppage time was 1 second;these were set as one cycle, and the forward and reverse rotations wererepeated.

At this time, the power application efficiency (the ratio of powerapplication time in one cycle) was 45.5%.

FIG. 27 shows a time chart of the driving conditions.

The nickel plated resin fine particles having a nickel plated layer asthe outermost layer thus obtained were observed under an opticalmicroscope, and all the particles existed as individually isolatedparticles without any aggregation.

Moreover, the average particle size of 300 of the nickel plated resinfine particles was 661.18 μm and the thickness of the nickel platedlayer was 5.40 μm. The variation coefficient of the particle size was2.7%, thereby indicating that the thickness of the nickel plated layerwas extremely uniform. Here, there were no particles influenced by amelt down base nickel plating layer due to the bipolar phenomenon.

EXAMPLE 28

A nickel plating layer was formed as a conductive base layer by anelectroless plating method on each of completely the same organic resinfine particles as Example 27; thus, electroless nickel plated fineparticles having an electroless nickel-film thickness of 2000 Å wereobtained. The specific gravity of the electroless nickel plated fineparticles thus obtained was 1.204.

The resulting nickel plated fine particles (105 g) were subjected tonickel plating on their surface by using a manufacturing device forconductive fine particles shown in FIG. 11.

Plating was carried out in the same manner as Example 27 except that thedriving conditions were altered as follows:

The number of revolutions of the treatment chamber was set so as toprovide a centrifugal effect of 28.6. The inner diameter of thetreatment chamber used was 280 mm, and the number of revolutions of thetreatment chamber was 427.5 rpm, the peripheral velocity thereof was376.0 m/min. The particle shifting time was 2 seconds, the powerapplication time was 3 seconds, the deceleration time was 1 second, andthe stoppage time was 1 second; these were set as one cycle, and theforward and reverse rotations were repeated.

At this time, the power application efficiency (the ratio of powerapplication time in one cycle) was 46.2%.

FIG. 28 shows a time chart of the driving conditions.

The nickel plated resin fine particles having a nickel plated layer asthe outermost layer thus obtained were observed under an opticalmicroscope, and all the particles existed as individually isolatedparticles without any aggregation.

Moreover, the average particle size of 300 of the nickel plated resinfine particles was 660.78 μm and the thickness of the nickel platedlayer was 5.20 μm. The variation coefficient of the particle size was2.5%, thereby indicating that the thickness of the nickel plated layerwas extremely uniform. Here, there were no particles influenced by amelt down base nickel plating layer due to the bipolar phenomenon.

EXAMPLE 29

A nickel plated layer was formed as a conductive base layer by anelectroless plating method on each of completely the same organic resinfine particles as Example 27; thus, electroless nickel plated fineparticles having an electroless nickel-film thickness of 2000 Å wereobtained. The specific gravity of the electroless nickel plated fineparticles thus obtained was 1.204.

The resulting nickel plated fine particles (105 g) were subjected tonickel plating on their surface by using a manufacturing device forconductive fine particles shown in FIG. 11.

Plating was carried out in the same manner as Example 27 except that thedriving conditions were altered as follows:

The number of revolutions of the treatment chamber was set so as toprovide a centrifugal effect of 3.2. The inner diameter of the treatmentchamber was 280 mm, and the number of revolutions of the treatmentchamber was 142.5 rpm, the peripheral velocity thereof was 125.3 m/min.The particle shifting time was 8 seconds, the power application time was5 seconds, the deceleration time was 1 second, and the stoppage time was0 second; these were set as one cycle, and the forward and reverserotations were repeated.

At this time, the power application efficiency (the ratio of powerapplication time in one cycle) was 35.7%.

FIG. 29 shows a time chart of the driving conditions.

The nickel plated resin fine particles having a nickel plated layer asthe outermost layer thus obtained were observed under an opticalmicroscope, and all the particles existed as individually isolatedparticles without any aggregation.

Moreover, the average particle size of 300 of the nickel plated resinfine particles was 659.46 μm and the thickness of the nickel platedlayer was 5.04 μm. The variation coefficient of the particle size was2.5%, thereby indicating that the thickness of the nickel plated layerwas extremely uniform. Here, there were no particles influenced by amelt down base nickel plating layer due to the bipolar phenomenon.

EXAMPLE 30

The nickel plated resin fine particles (140 g) (particle size: 661.18μm, variation coefficient: 2.7%, specific gravity: 1.57) having a nickelplating layer as the outermost surface, obtained in Example 27, weresubjected to eutectic solder plating on their surface by using amanufacturing device for conductive fine particles shown in FIG. 11.

A porous member, which was formed by affixing a nylon filter sheet 20having a pore size of 10 μm and a thickness of 10 μm onto the uppersurface of a plate-shaped porous support 22 having a pore size of 100 μmand a thickness of 6 mm, made from high density polyethylene, was usedas the porous member 21.

An alloy of tin (Sn):lead (Pb)=6:4 was used as the anode 2 a.

Acid bath (537A) (product by Ishihara Yakuhin Kogyo K.K.) was used asthe plating solution.

The composition of the plating solution was adjusted so that the totalmetal concentration was 21.39 g/L, the metal ratio in the bath, Sn was65.3%, alkanol sulfonic acid was 106.4 g/L, and an additive was 40 mL.

Power was applied across the electrodes under the conditions that thetemperature of the plating solution was 20° C., the current was 40.5 A,and the current density was 0.5 A/dm². The total power application timewas 105 minutes.

The driving condition was set so that the number of revolutions of thetreatment chamber provides a centrifugal effect of 10.3. The treatmentchamber used here had an inner diameter of 280 mm, the number ofrevolutions of the treatment chamber was 256.5 rpm, and the peripheralvelocity thereof was 225.6 m/min. The driving pattern of the powerapplication process was set so that one cycle included the particleshifting time of 2 seconds, the power application time of 3 seconds, thedeceleration time of 0.5 seconds, and the stoppage time of 2 seconds;thus, in this cycle, the forward and reverse rotations were repeated.

At this time, the power application efficiency (the ratio of powerapplication time in one cycle) was 40%.

FIG. 30 shows a time chart of the driving conditions.

The eutectic solder plated resin fine particles having an eutecticsolder layer as the outermost layer thus obtained were observed under anoptical microscope, and all the particles existed as individuallyisolated particles.

Moreover, the average particle size of 300 of the eutectic solder platedresin fine particles was 693.06 μm and the thickness of the solderplated layer was 15.94 μm. The variation coefficient of the particlesize was 3.8%, thereby indicating that the thickness of the solderplated layer was extremely uniform. The resulting solder coat wasanalyzed by the atomic absorption method, and Sn was 61.7%, which provedits eutectic composition. Here, there were no particles influenced by amelt down base nickel plating layer due to the bipolar phenomenon.

EXAMPLE 31

A nickel plated layer was formed as a conductive base layer by anelectroless plating method on each of organic resin fine particleshaving a specific gravity of 1.19, an average particle size of 106.42μm, a standard deviation of 1.70 μm and a variation coefficient of 1.6%,formed by copolymerizing styrene and divinylbenzene; thus, electrolessnickel plated fine particles having an electroless nickel-film thicknessof 2000 Å were obtained. The specific gravity of the electroless nickelplated fine particles thus obtained was 1.276.

The resulting nickel plated fine particles (21.6 g) were subjected tonickel plating on their surface by using a manufacturing device forconductive fine particles shown in FIG. 11.

A porous member, which was formed by affixing a nylon filter sheet 20having a pore size of 10 μm and a thickness of 10 μm onto the uppersurface of a plate-shaped porous support 22 having a pore size of 100 μmand a thickness of 6 mm, made from high density polyethylene, was usedas the porous member 21.

Metal nickel was used as the anode 2 a.

A Watt bath was used as the plating solution.

The composition of the plating solution was 68 g/L of nickelconcentration, 42 g/L of nickel chloride, nickel sulfate 260 g/L, and 42g/L of boric acid. The plating solution had a pH of 3.7 and a specificgravity of 1.18.

Power was applied across the electrodes under the conditions that thetemperature of the plating solution was 50° C., the current was 33 A,and the current density was 0.35 A/dm². Here, the total powerapplication time was approximately 50 minutes.

With respect to the driving conditions, the number of revolutions of thetreatment chamber was set so as to provide a centrifugal effect of 10.3.The inner diameter of the treatment chamber used in this case was 280mm, and the number of revolutions of the treatment chamber was 256.5rpm, and the peripheral velocity thereof was 225.6 m/min. The particleshifting time was 4 seconds, the power application time was 5 seconds,the deceleration time was 1 second, and the stoppage time was 1 second;these were set as one cycle, and the forward and reverse rotations wererepeated.

At this time, the power application efficiency (the ratio of powerapplication time in one cycle) was 45.5%.

FIG. 27 shows a time chart of the driving conditions.

The nickel plated resin fine particles having a nickel plated layer asthe outermost layer thus obtained were observed under an opticalmicroscope, and all the particles existed as individually isolatedparticles without any aggregation.

Moreover, the average particle size of 300 of the nickel plated resinfine particles was 111.06 μm and the thickness of the nickel platedlayer was 2.32 μm. The variation coefficient of the particle size was2.4%, thereby indicating that the thickness of the nickel plated layerwas extremely uniform. Here, there were no particles influenced by amelt down base nickel plating layer due to the bipolar phenomenon.

EXAMPLE 32

The nickel plated resin fine particles (40 g)(particle size: 111.06 μm,variation coefficient: 2.4%, specific gravity: 2.111) having a nickelplating layer as the outermost 35 surface, obtained in Example 31, weresubjected to eutectic solder plating on their surface by using amanufacturing device for conductive fine particles shown in FIG. 11.

A porous member, which was formed by affixing a nylon filter sheet 20having a pore size of 10 μm and a thickness of 10 μm onto the uppersurface of a plate-shaped porous support 22 having a pore size of 100 μmand a thickness of 6 mm, made from high density polyethylene, was usedas the porous member 21.

An alloy of tin (Sn):lead (Pb)=6:4 was used as the anode 2 a.

Acid bath (537A) produced by Ishihara Yakuhin Kogyo K.K. was used as theplating solution.

The composition of the plating solution was adjusted so that the totalmetal concentration was 21.39 g/L, and the metal ratio in the bath was65.3% of Sn, 106.4 g/L of alkanol sulfonic acid, and 40 mL of anadditive.

Power was applied across the electrodes under the conditions that thetemperature of the plating solution was 20° C., the current was 40.5 A,and the current density was 0.5 A/dm². The total power application timewas 105 minutes.

The driving condition was set so that the number of revolutions of thetreatment chamber provides a centrifugal effect of 10.3. The treatmentchamber used here had an inner diameter of 280 mm, the number ofrevolutions was 256.5 rpm, and the peripheral velocity thereof was 225.6m/min. The particle shifting time was 3 seconds, the power applicationtime was 2 seconds, the deceleration time was 0.5 second, and thestoppage time of 2 seconds; thus, these were set as one cycle, and theforward and reverse rotations were repeated.

At this time, the power application efficiency (the ratio of powerapplication time in one cycle) was 26.7%.

FIG. 31 shows a time chart of the driving conditions.

The eutectic solder plated resin fine particles having an eutecticsolder plated layer as the outermost layer thus obtained were observedunder an optical microscope, and all the particles existed asindividually isolated particles.

Moreover, the average particle size of 300 of the nickel solder platedresin fine particles was 119.3 μm and the thickness of the solder platedlayer was 4.12 μm. The variation coefficient of the particle size was3.6%, thereby indicating that the thickness of the solder plated layerwas extremely Uniform. The resulting solder coat was analyzed by theatomic absorption method, and Sn was 62.6%, which proved its eutecticcomposition. Here, there were no particles influenced by a melt downbase nickel plating layer due to the bipolar phenomenon.

EXAMPLE 33

A nickel plated layer was formed as a conductive base layer by anelectroless plating method on each of organic resin fine particleshaving a specific gravity of 1.19, an average particle size of 19.74 μm,a standard deviation of 0.28 μm and a variation coefficient of 1.4%,formed by copolymerizing styrene and divinylbenzene; thus, electrolessnickel plated fine particles having an electroless nickel-film thicknessof 2000 Å were obtained. The specific gravity of the electroless nickelplated fine particles thus obtained was 1.637.

The resulting nickel plated fine particles (4.8 g) were subjected tonickel plating on their surface by using a manufacturing device forconductive fine particles shown in FIG. 11.

A porous member, which was formed by affixing a nylon filter sheet 20having a pore size of 10 μm and a thickness of 10 μm onto the uppersurface of a plate-shaped porous support 22 having a pore size of 100 μmand a thickness of 6 mm, made from high density polyethylene, was usedas the porous member 21.

Metal nickel was used as the anode 2 a.

A Watt bath was used as the plating solution.

The composition of the plating solution was 68 g/L of nickelconcentration, 42 g/L of nickel chloride, 260 g/L of nickel sulfate, and42 g/L of boric acid. The plating solution had a pH of 3.7 and aspecific gravity of 1.18.

Power was applied across the electrodes under the conditions that thetemperature of the plating solution was 50° C., the current was 33 A,and the current density was 0.35 A/dm². Here, the total powerapplication time was approximately 50 minutes.

With respect to the driving conditions, the number of revolutions of thetreatment chamber was set so as to provide a centrifugal effect of 10.3.The inner diameter of the treatment chamber used in this case was 280mm, and the number of revolutions of the treatment chamber was 256.5rpm, and the peripheral velocity thereof was 225.6 m/min. The particleshifting time was 7 seconds, the power application time was 3 seconds,the deceleration time was 0.5 second, and the stoppage time was 2seconds; these were set as one cycle, and the forward and reverserotations were repeated.

At this time, the power application efficiency (the ratio of powerapplication time in one cycle) was 24.0%.

FIG. 32 shows a time chart of the driving conditions.

The nickel plated resin fine particles having a nickel plated layer asthe outermost layer thus obtained were observed under an opticalmicroscope, and all the particles existed as individually isolatedparticles without any aggregation. Moreover, the average particle sizeof 300 of the nickel plated resin fine particles was 22.62 μm and thethickness of the nickel plated layer was 1.44 μm. The variationcoefficient of the particle size was 2.6%, thereby indicating that thethickness of the nickel plated layer was extremely uniform. Here, therewere no particles influenced by a melt down base nickel plating layerdue to the bipolar phenomenon.

EXAMPLE 34

The nickel plated resin fine particles (14.0 g) (particle size: 22.62 m,variation coefficient: 2.6%, specific gravity: 3.759) having a nickelplating layer as the outermost layer, obtained in Example 33, weresubjected to eutectic solder plating on their surface by using amanufacturing device for conductive fine particles shown in FIG. 11.

A porous member, which was formed by affixing a nylon filter sheet 20having a pore size of 10 μm and a thickness of 10 μm onto the uppersurface of a plate-shaped porous support 22 having a pore size of 100 μmand a thickness of 6 mm, made from high density polyethylene, was usedas the porous member 21.

An alloy of tin (Sn):lead (Pb)=6:4 was used as the anode 2 a.

Acid bath (537A) produced by Ishihara Yakuhin Kogyo K.K. was used as theplating solution.

The composition of the plating solution was adjusted so that the totalmetal concentration was 21.39 g/L, the metal ratio in the bath was 65.3%of Sn, 106.4 g/L of alkanol sulfonic acid, and 40 mL of an additive.

Power was applied across the electrodes under the conditions that thetemperature of the plating solution was 20° C., the current was 40.5 A,and the current density was 0.5 A/dm². The total power application timewas 105 minutes.

The driving condition was set so that the number of revolutions of thetreatment chamber provides a centrifugal effect of 10.3. The treatmentchamber used here had an inner diameter of 280 mm, the number ofrevolutions of the treatment chamber was 256.5 rpm, and the peripheralvelocity thereof was 225.6 m/min. The particle shifting time was 5seconds, the power application time was 1.5 seconds, the decelerationtime was 0.5 second, and the stoppage time of 2 seconds; thus, therewere set as one cycle, and the forward and reverse rotations wererepeated.

At this time, the power application efficiency (the ratio of powerapplication time in one cycle) was 16.7%.

FIG. 33 shows a time chart of the driving conditions.

The eutectic solder plated resin fine particles having an eutecticsolder plated layer as the outermost layer thus obtained were observedunder an optical microscope, and all the particles existed asindividually isolated particles.

Moreover, the average particle size of 300 of the nickel plated resinfine particles was 26.59 μm and the thickness of the solder plated layerwas 1.99 μm. The variation coefficient of the particle size was 3.8%,thereby indicating that the thickness of the solder plated layer wasextremely uniform. The resulting solder coat was analyzed by the atomicabsorption method, and Sn was 59.7%, which proved its eutecticcomposition. Here, there were no particles influenced by a melt downbase nickel plating layer due to the bipolar phenomenon.

COMPARATIVE EXAMPLE 14

A nickel plating layer was formed as a conductive base layer on each ofthe completely same organic resin fine particles as Example 27 by usingan electroless plating method; thus, electroless nickel plated fineparticles having an electroless nickel film thickness of 2000 Å wereobtained. The resulting electroless nickel plating fine particles had aspecific gravity of 1.204.

The nickel plated fine particles (105 g) thus obtained were subjected tonickel plating on their surface by using a manufacturing device forconductive fine particles shown in FIG. 11.

The plating was carried out in the same manner as Example 27 except thatthe driving conditions were altered as follows:

The number of revolutions of the treatment chamber was set so as toprovide a centrifugal effect of 47.4. The inner diameter of thetreatment chamber used in this case was 280 mm, the number ofrevolutions of the treatment chamber was 550.0 rpm, and the peripheralvelocity thereof was 483.8 m/min. The particle shifting time was 1second, the power application time was 3 seconds, the deceleration timewas 1 second, and the stoppage time was 1 second; these were set as onecycle, and the forward and reverse rotations were repeated.

At this time, the power application efficiency (the ratio of powerapplication time in one cycle) was 45.5%.

FIG. 34 shows a time chart of the driving conditions.

In the case of the centrifugal effect of not less than 40.0, the time ittook for the fine particles to reach the contact ring was greatlyshortened; however, since the plating solution, which had been subjectedto a force in the outer circumferential direction due to the centrifugalforce, formed a vortex having a mortar-like shape inside the treatmentchamber, with the result that the anode placed in the center of thetreatment chamber was exposed, failing to flow current and to carry outplating.

COMPARATIVE EXAMPLE 15

A nickel plating layer was formed as a conductive base layer on each ofthe completely same organic resin fine particles as Example 27 by usingan electroless plating method; thus, electroless nickel plated fineparticles having an electroless nickel film thickness of 2000 Å wereobtained. The resulting electroless nickel plating fine particles had aspecific gravity of 1.204.

The nickel plated fine particles (105 g) thus obtained were subjected tonickel plating on their surface by using a manufacturing device forconductive fine particles shown in FIG. 11.

The plating was carried out in the same manner as Example 27 except thatthe driving conditions were altered as follows:

The number of revolutions of the treatment chamber was set so as toprovide a centrifugal effect of 1.6. The inner diameter of the treatmentchamber used in this case was 280 mm, the number of revolutions of thetreatment chamber was 99.8 rpm, and the peripheral velocity thereof was87.7 m/min. The particle shifting time was 10 seconds, the powerapplication time was 5 seconds, the deceleration time was 1 second, andthe stoppage time was 1 second; these were set as one cycle, and theforward and reverse rotations were repeated.

At this time, the power application efficiency (the ratio of powerapplication time in one cycle) was 29.4%.

FIG. 35 shows a time chart of the driving conditions.

In the case of the centrifugal effect of not more than 2.0, the fineparticles hardly approached the contact ring even when the particleshifting time was set to 10 seconds, the bipolar phenomenon occurred,causing melt-down in the electroless plating layers of almost all theparticles, and the as a result failing to carry out plating.

COMPARATIVE EXAMPLE 16

A nickel plating layer was formed as a conductive base layer on each ofthe completely same organic resin fine particles as Example 27 by usingan electroless plating method; thus, electroless nickel plated fineparticles having an electroless nickel film thickness of 2000 Å wereobtained. The resulting electroless nickel plating fine particles had aspecific gravity of 1.204.

The nickel plated fine particles (105 g) thus obtained were subjected tonickel plating on their surface by using a manufacturing device forconductive fine particles shown in FIG. 11.

The plating was carried out in the same manner as Example 27 except thatthe driving conditions were altered as follows:

The number of revolutions of the treatment chamber was set so as toprovide a centrifugal effect of 28.6. The inner diameter of thetreatment chamber used in this case was 280 mm, the number ofrevolutions of the treatment chamber was 427.5 rpm, and the peripheralvelocity thereof was 376.0 m/min. The particle shifting time was 12seconds, the power application time was 3 seconds, the deceleration timewas 1 second, and the stoppage time was 1 second; these were set as onecycle, and the forward and reverse rotations were repeated.

At this time, the power application efficiency (the ratio of powerapplication time in one cycle) was 17.6%.

FIG. 36 shows a time chart of the driving conditions.

Even in the case of the centrifugal effect of 28.6 which was within theplating permissible range in Example 2, since the particle shifting timewas set too long, the plating solution, which had been subjected to aforce in the outer circumferential direction due to the centrifugalforce, formed a vortex having a mortar-like shape inside the treatmentchamber, with the result that the anode placed in the center of thetreatment chamber was exposed. As a result, the current did not flow andplating did not be curried out.

COMPARATIVE EXAMPLE 17

A nickel plating layer was formed as a conductive base layer on each ofthe completely same organic resin fine particles as Example 27 by usingan electroless plating method; thus, electroless nickel plated fineparticles having an electroless nickel film thickness of 2000 Å wereobtained. The resulting electroless nickel plating fine particles had aspecific gravity of 1.204.

The nickel plated fine particles (105 g) thus obtained were subjected tonickel plating on their surface by using a manufacturing device forconductive fine particles shown in FIG. 11.

The plating was carried out in the same manner as Example 27 except thatthe driving conditions were altered as follows:

The number of revolutions of the treatment chamber was set so as toprovide a centrifugal effect of 28.6. The inner diameter of thetreatment chamber used in this case was 280 mm, the number ofrevolutions of the treatment chamber was 427.5 rpm, and the peripheralvelocity thereof was 376.0 m/min. The particle shifting time was 0seconds, the power application time was 5 seconds, the deceleration timewas 1 second, and the stoppage time was 1 second; these were set as onecycle, and the forward and reverse rotations were repeated.

At this time, the power application efficiency (the ratio of powerapplication time in one cycle) was 71.4%.

FIG. 37 shows a time chart of the driving conditions.

Since the power application was started simultaneously with the rotationof the treatment chamber, an electric current was allowed to flow whilethe fine particles were shifting toward the contact ring. As a result,the bipolar phenomenon occurred, causing melt-down in the electrolessplating layers of almost all the fine particles, and failing to carryout plating.

When the resulting fine particles were observed under an opticalmicroscope, it was found that approximately 90% of the fine particleshad melt-down electroless plating layers due to the bipolar phenomenon,and were left as exposed resin fine particles.

COMPARATIVE EXAMPLE 18

A nickel plating layer was formed as a conductive base layer on each ofthe completely same organic resin fine particles as Example 27 by usingan electroless plating method; thus, electroless nickel plated fineparticles having an electroless nickel film thickness of 2000 Å wereobtained. The resulting electroless nickel plating fine particles had aspecific gravity of 1.204.

The nickel plated fine particles (105 g) thus obtained were subjected tonickel plating on their surface by using a manufacturing device forconductive fine particles shown in FIG. 11.

The plating was carried out in the same manner as Example 27 except thatthe driving conditions were altered as follows: The number ofrevolutions of the treatment chamber was set so as to provide acentrifugal effect of 10.3. The inner diameter of the treatment chamberused in this case was 280 mm, the number of revolutions of the treatmentchamber was 256.5 rpm, and the peripheral velocity thereof was 225.6m/min. The particle shifting time was 4 seconds, the power applicationtime was 5 seconds, the deceleration time was 1 second, and the stoppagetime was 12 seconds; these were set as one cycle, and the forward andreverse rotations were repeated.

At this time, the power application efficiency (the ratio of powerapplication time in one cycle) was 22.7%.

FIG. 38 shows a time chart of the driving conditions.

The nickel plated resin fine particles having a nickel plating layer asthe outermost layer thus obtained were observed under an opticalmicroscope, and all the particles existed as individually isolatedparticles without any aggregation.

Moreover, the average particle size of 300 of the nickel plated resinfine particles was 660.33 μm and the thickness of the nickel platedlayer was 4.98 μm. The variation coefficient of the particle size was2.8%, thereby indicating that the thickness of the nickel plated layerwas extremely uniform. Here, there were no particles influenced by amelt down base nickel plating layer due to the bipolar phenomenon.

The fine particles thus obtained were the same as those of Example 1;however, since the stoppage time was set too long, the efficiency becameinferior and the total plating times took approximately twice longerthan that of Example 1.

Table 10 shows the results of Examples 27 to 34 as well as ComparativeExamples 14 to 18. TABLE 10 Particle Power Particle Particle PeripheralNumber of shifting Power Decelera- Stoppage application size specificCentrifugal velocity revolutions time application tion time timeefficiency (μm) gravity effect (m/min.) (rpm) (sec.) time (sec.) (sec.)(sec.) (%) Evaluation Ex. 27 650 1.20 10.3 225.6 256.5 4 5 1 1 45.5 ◯Ex. 28 650 1.20 28.6 376 427.5 2 3 0.5 1 46.2 ◯ Ex. 29 650 1.20 3.2125.3 142.5 8 5 1 0 35.7 ◯ Ex. 30 650 1.57 10.3 225.6 256.5 2 3 0.5 240.0 ◯ Ex. 31 106 1.28 10.3 225.6 256.5 4 5 1 1 45.5 ◯ Ex. 32 106 2.1110.3 225.6 256.5 3 2 0.5 2 26.7 ◯ Ex. 33 20 1.64 10.3 225.6 256.5 7 30.5 2 24.0 ◯ Ex. 34 20 3.76 10.3 225.6 256.5 5 1.5 0.5 2 16.7 ◯ Compar.650 1.20 47.4 483.8 550 1 3 1 1 50.0 X Ex. 14 Compar. 650 1.20 1.6 87.799.8 10 5 1 1 29.4 X Ex. 15 Compar. 650 1.20 28.6 376 427.5 12 3 1 117.6 Δ Ex. 16 Compar. 650 1.20 28.6 376 427.5 0 5 1 1 71.4 X Ex. 17Compar. 650 1.20 10.3 225.6 256.5 4 5 1 12 22.7 Δ Ex. 18

EXAMPLE 35

A nickel plated layer was formed as a conductive base layer by anelectroless plating method on each of organic resin fine particleshaving a specific gravity of 1.19, an average particle size 650.8 μm, astandard deviation 9.75 μm and a variation coefficient of 1.5%, formedby copolymerizing styrene and divinylbenzene; thus, electroless nickelplated fine particles having a nickel-film thickness of 2000 Å wereobtained. The specific gravity of the electroless nickel plated fineparticles thus obtained was 1.204.

The resulting nickel plated fine particles (105 g) were subjected tonickel plating on their surface by using a manufacturing device forconductive fine particles shown in FIG. 11.

A porous member, which was formed by affixing a nylon filter sheet 20having a pore size of 10 μm and a thickness of 10 μm onto the uppersurface of a plate-shaped porous support 22 having a pore size of 100 μmand a thickness of 6 mm, made from high density polyethylene, was usedas the porous member 21.

Metal nickel was used as the anode 2 a.

A Watt bath was used as the plating solution.

The composition of the plating solution was 42 g/L of nickelconcentration, 39 g/L of nickel chloride, 150 g/L of nickel sulfate, and45 g/L of boric acid. The plating solution had a pH of 3.8 and aspecific gravity of 1.11.

Power was applied across the electrodes under the conditions that thetemperature of the plating solution was 50° C., the current was 32 A,and the current density was 0.4 A/dm². Here, the total power applicationtime was approximately 80 minutes.

With respect to the driving conditions, the number of revolutions of thetreatment chamber was set so as to provide a centrifugal effect of 10.3.The inner diameter of the treatment chamber used in this case was 280mm, and the number of revolutions of the treatment chamber was 256.5rpm, and the peripheral velocity thereof was 225.6 m/min.

With respect to the driving pattern in the plating initial stage, theparticle shifting time was 4 seconds, the power application time was 5seconds, the deceleration time was 1 second, and the stoppage time was 1second; these were set as one cycle, and the forward and reverserotations were repeated. Approximately 39 minutes after the platingstart, the fine particles were sampled and observed under an opticalmicroscope, and all the particles existed as individually isolatedparticles without any aggregation. Moreover, the average particle sizeof 100 of the nickel plated resin fine particles was 652.82 μm and thethickness of the nickel plated layer was 1.02 μm, and the specificgravity thereof was 1.276. Here, the driving pattern was altered so asto shorten the particle shifting time so that one cycle included theparticle shifting time of 2 seconds, the power application time of 5seconds, the deceleration time of 1 second and the stoppage time of 1second, and the forward and reverse rotations were repeated; thus, theplating was continued. The total plating time was approximately 168minutes.

The nickel plated resin fine particles having a nickel plated layer asthe outermost layer thus obtained were observed under an opticalmicroscope, and all the particles existed as individually isolatedparticles without any aggregation.

Moreover, the average particle size of 300 of the nickel plated resinfine particles was 661.06 μm and the thickness of the nickel platedlayer was 5.14 μm. The variation coefficient of the particle size was2.5%, thereby indicating that the thickness of the nickel plated layerwas extremely uniform. Here, there were no particles influenced by amelt down base nickel plating layer due to the bipolar phenomenon.

From the above-mentioned plating film thickness and the total platingtime, it was found that the plating time per 1 μm of coat film wasapproximately 32.7 minutes.

EXAMPLE 36

By using completely the same electroless nickel plated fine particles asExample 35, plating was carried out in the same manner as Example 35except that the driving conditions were altered as follows:

With respect to the driving pattern in the plating initial stage, theparticle shifting time was 4 seconds, the power application time was 5seconds, the deceleration time was 1 second, and the stoppage time was 1second; these were set as one cycle, and the forward and reverserotations were repeated. Approximately 37 minutes after the platingstart, the fine particles were sampled and observed under an opticalmicroscope, and all the particles existed as individually isolatedparticles without any aggregation. Moreover, the average particle sizeof 100 of the nickel plated resin fine particles was 652.74 μm and thethickness of the nickel plated layer was 0.98 μm and the specificgravity thereof was 1.273. Here, the driving pattern was altered so asto shorten the particle shifting time so that one cycle included theparticle shifting time of 0.5 seconds, the power application time of 5seconds, the deceleration time of 1 second and the stoppage time of 1second, and the forward and reverse rotations were repeated; thus, theplating was continued. The total plating time was approximately 143minutes.

The nickel plated resin fine particles having a nickel plated layer asthe outermost layer thus obtained were observed under an opticalmicroscope, and all the particles existed as individually isolatedparticles without any aggregation.

Moreover, the average particle size of 300 of the nickel plated resinfine particles was 660.88 μm and the thickness of the nickel platedlayer was 5.05 μm. The variation coefficient of the particle size was2.5%, thereby indicating that the thickness of the nickel plated layerwas extremely uniform. Here, there were no particles influenced by amelt down base nickel plating layer due to the bipolar phenomenon.

From the above-mentioned plating film thickness and the total platingtime, it was found that the plating time per 1 m of coat film wasapproximately 28.3 minutes.

EXAMPLE 37

By using completely the same electroless nickel plated fine particles asExample 35, plating was carried out in the same manner as Example 35except that the driving conditions were altered as follows:

With respect to the driving pattern in the plating initial stage, theparticle shifting time was 4 seconds, the power application time was 5seconds, the deceleration time was 1 second, and the stoppage time was 1second; these were set as one cycle, and the forward and reverserotations were repeated. At approximately 23 minutes after the platingstart, the fine particles were sampled and observed under an opticalmicroscope, and all the particles existed as individually isolatedparticles without any aggregation. Moreover, the average particle sizeof 100 of the nickel plated resin fine particles was 650.00 μm and thethickness of the nickel plated layer was 0.61 μm, and the specificgravity thereof was 1.247. Here, the driving pattern was altered so asto shorten the particle shifting time so that one cycle included theparticle shifting time of 0.5 seconds, the power application time of 5seconds, the deceleration time of 1 second and the stoppage time of 1second, and the forward and reverse rotations were repeated; thus, theplating was continued. The total plating time was approximately 140minutes.

The nickel plated resin fine particles having a nickel plated layer asthe outermost layer thus obtained were observed under an opticalmicroscope, and all the particles existed as individually isolatedparticles without any aggregation.

Moreover, the average particle size of 300 of the nickel plated resinfine particles was 660.98 μm and the thickness of the nickel platedlayer was 5.10 μm. The variation coefficient of the particle size was2.6%, thereby indicating that the thickness of the nickel plated layerwas extremely uniform. Here, there were no particles influenced by amelt down base nickel plating layer due to the bipolar phenomenon.

From the above-mentioned plating film thickness and the total platingtime, it was found that the plating time per 1 μm of coat film wasapproximately 27.5 minutes.

COMPARATIVE EXAMPLE 19

By using completely the same electroless nickel plated fine particles asExample 35, plating was carried out in the same manner as Example 35except that the driving conditions were altered as follows:

With respect to the driving pattern in the plating initial stage, theparticle shifting time was 12 seconds, the power application time was 5seconds, the deceleration time was 1 second, and the stoppage time was 1second; these were set as one cycle, and the forward and reverserotations were repeated.

Since the particle shifting time was extended to 12 seconds, the platingsolution, which had been subjected to a force in the outercircumferential direction due to the centrifugal force, formed a vortexhaving a mortar-like shape inside the treatment chamber, with the resultthat the anode placed in the center of the treatment chamber wasexposed, failing to flow current and to carry out plating.

COMPARATIVE EXAMPLE 20

By using completely the same electroless nickel plated fine particles asExample 35, plating was carried out in the same manner as Example 9except that the driving conditions were altered as follows:

With respect to the driving pattern in the plating initial stage, theparticle shifting time was 4 seconds, the power application time was 5seconds, the deceleration time was 1 second, and the stoppage time was 1second; these were set as one cycle, and the forward and reverserotations were repeated. Approximately 44 minutes after the platingstart, the fine particles were sampled and observed under an opticalmicroscope, and all the particles existed as individually isolatedparticles without any aggregation. Moreover, the average particle sizeof 100 of the nickel plated resin fine particles was 653.06 μm and thethickness of the nickel plated layer was 1.14 μm, and the specificgravity thereof was 1.276. Here, the driving pattern was altered so asto shorten the particle shifting time so that one cycle included theparticle shifting time of 0 seconds, the power application time of 5seconds, the deceleration time of 1 second and the stoppage time of 1second, and the forward and reverse rotations were repeated; thus, theplating was continued. The total plating time was approximately 140minutes.

The nickel plated resin fine particles having a nickel plated layer asthe outermost layer thus obtained were observed under an opticalmicroscope, and all the particles existed as individually isolatedparticles without any aggregation.

However, since the particle shifting time was set to 0 after thealternation of the driving pattern, power was applied simultaneously asthe particles started to shift toward the cathode; therefore, thebipolar phenomenon occurred until they contacted the cathode, with theresult that a few particles had melt-down electroless nickel layers,although the number thereof was small.

Moreover, the average particle size of 300 of the nickel plated resinfine particles was 657.76 μm and the thickness of the nickel platedlayer was 3.69 μm. The variation coefficient of the particle size was13.2%, thereby indicating that the thickness of the nickel plated layerwas extremely ununiform.

Table 11 shows Examples 35 to 37 and Comparative Examples 19 and 20.TABLE 11 Driving pattern Initial driving after alternation pattern(sec.) (sec.) Power Power Start time Film thickness Particle appli-Deceler- Stop- Particle appli- Deceler- Stop- of pattern at the time ofshifting cation ation page shifting cation ation page alternationalternation zebra time time time time time time time time (min.) (μm)Ex. 35 4 5 1 1 2 5 1 1 39 1.02 Ex. 36 4 5 1 1 0.5 5 1 1 37 0.98 Ex. 37 45 1 1 0.5 5 1 1 23 0.61 Compar. 12 5 1 1 — — — — — — Ex. 19 Compar. 4 51 1 0 5 1 1 44 1.14 Ex. 20 Film thickness Plating time at the time ofVariation per 1 μm of completion of coefficient Total plating coat filmplating (μm) (%) time (min.) (min./μm) Ex. 35 5.14 2.5 168 32.68 Ex. 365.05 2.7 143 28.32 Ex. 37 5.10 2.6 140 27.45 Compar. Formation ofvortex, no current flow, no plating Ex. 19 Compar. 3.69 13.2 Bipolarphenomenon occurred Ex. 20

EXAMPLE 38

A nickel coating with a thickness of 0.2 μm was formed by electrolessplating on a divinylbenzene polymer having an average particle size of23 μm, a CV value of 5%, an aspect ratio of 1.04, a K value of 400kgf/mm² at the time of 10% deformation and a recovery rate of 60%.Thereafter, a filter was formed on the outer circumferential portion ofa rotatable electroplating device having a cathode on thecircumferential portion and an anode that was placed in a manner so asnot to contact the cathode, and while this is being continuouslyrotated, stopped, subjected to a ultrasonic process, and reversed, goldwas plated with a thickness of 0.8 μm with a plating solution beingsupplied thereto; thus, conductive fine particles having a platingthickness variation coefficient of 10%, an average particle size 25 μm,a CV value of 5%, and an aspect ratio of 1.04 were formed.

Here, the average particle size, the CV value (standarddeviation/average particle size) and the aspect ratio are valuesobtained through observation of 300 particles under an electronicmicroscope. The K value is represented by:K=(3/√{square root over ( )}2)·F·S^(−3/2)·R^(−1/2)

where F is a load value (kgf) at 20° C. at the time of 10% compresseddeformation, S represents a compressed dislocation (mm) and R is aradius (mm).

The recovery rate is a value after the 10% compressed deformation at 20°C.

The plating thickness and the plating variation coefficient were foundthrough observation on cross-sections of 20 plating particles under anelectronic microscope.

The conductive fine particles were mixed with, and dispersed in athermosetting epoxy resin with a concentration of 10% so that ananisotropic conductive paste was formed. This was applied to aglass-epoxy copper coated substrate (thickness: 1.6 mm, wiring width: 80μm, electrode pitch: 200 μm) with a virtually uniform thickness by ascreen printing method.

On this is superposed a polyimide film substrate (thickness: 50 μm,wiring width: 80 μm, electrode pitch: 200 μm) with a thickness of 100μm, and this was then heated and pressed at 150° C. for two minutes;thus, a conductive connecting element was formed.

This conductive connecting element had a sufficiently low connectingresistivity of 0.002Ω, and a connecting resistance between the adjacentelectrodes was not less than 1×10⁹, thereby providing a sufficientline-to-line insulating property.

Cooling and heating cycle tests were carried out 1000 times in the rangeof −40 to 85° C.; however, the connecting resistance virtually showed nochange. Moreover, these tests were carried out as many as 5000 times;however, the connecting resistance virtually showed no change.

Furthermore, the conductive fine particles were immersed into hot waterof 120° C. for 24 hours, and then subjected to the same tests; however,no change was found in the connecting resistivity and the insulatingproperty.

Here, the electric resistivity can be reduced by increasing theconcentration of the conductive fine particles in the anisotropicconductive paste, the concentration of the conductive fine particles wasgradually increased, and no leakage occurred between the electrodesuntil the concentration had reached 35%.

EXAMPLE 39

A nickel coating with a thickness of 0.1 μm was formed by electrolessplating on a divinylbenzene polymer having an average particle size of11 μm, a CV value of 10%, an aspect ratio of 1.09, a K value of 430kgf/mm² and a recovery rate of 50%, with the other factors being thesame as Example 38. Thereafter, gold was plated with a thickness of 0.4μm; thus, conductive fine particles having a plating thickness variationcoefficient of 20%, 12 μm of an average particle size, 10% of a CVvalue, and 1.09 of an aspect ratio were formed.

These conductive fine particles were subjected to the same tests asExample 38, and the results showed that the conductive connectingelement had a sufficiently low connecting resistivity of 0.004Ω, and aconnecting resistance between the adjacent electrodes was not less than1×10⁹, thereby providing a sufficient line-to-line insulating property.

Cooling and heating cycle tests were carried out 1000 times in the rangeof −40 to 85° C.; however, the connecting resistance virtually showed nochange. Moreover, these tests were carried out as many as 5000 times;however, the connecting resistance virtually showed no change.

Furthermore, the conductive fine particles were immersed into hot waterof 120° C. for 24 hours, and then subjected to the same tests; however,no change was found in the connecting resistivity and the insulatingproperty.

Here, the concentration of the conductive fine particles in theanisotropic conductive paste was gradually increased, and no leakageoccurred between the electrodes until the concentration had reached 30%.

EXAMPLE 40

A nickel coating with a thickness of 0.2 μm was formed by electrolessplating on a crosslinking acrylonitrile copolymer having an averageparticle size of 58 μm, a CV value of 5%, an aspect ratio of 1.04, a Kvalue of 600 kgf/mm² and a recovery rate of 70%, with the other factorsbeing the same as Example 38. Thereafter, gold was plated with athickness of 0.8 μm; thus, conductive fine particles having a platingthickness variation coefficient of 10%, an average particle size 60 μm,a CV value of 5%, and an aspect ratio of 1.04 were formed.

These conductive fine particles were subjected to the same tests asExample 38, and the results showed that the conductive connectingelement had a sufficiently low connecting resistivity of 0.004Ω, and aconnecting resistance between the adjacent electrodes was not less than1×10⁹, thereby providing a sufficient line-to-line insulating property.

Cooling and heating cycle tests were carried out 1000 times in the rangeof −40 to 85° C.; however, the connecting resistance virtually showed nochange. Moreover, these tests were carried out as many as 5000 times;however, the connecting resistance virtually showed no change.

Furthermore, the conductive fine particles were immersed into hot waterof 120° C. for 24 hours, and then subjected to the same tests; however,no change was found in the connecting resistivity and the insulatingproperty.

Here, the concentration of the conductive fine particles in theanisotropic conductive paste was gradually increased, and no leakageoccurred between the electrodes until the concentration had reached 25%.

EXAMPLE 41

A nickel coating with a thickness of 0.2 μm was formed by electrolessplating on a divinylbenzene polymer having an average particle size of23 μm, a CV value of 15%, an aspect ratio of 1.1, a K value of 400kgf/mm² and a recovery rate of 60%, with the other factors being thesame as Example 38. Thereafter, gold was plated with a thickness of 0.8μm; thus, conductive fine particles having a plating thickness variationcoefficient of 10%, an average particle size 25 μm, a CV value of 15%,and an aspect ratio of 1.1 were formed.

These conductive fine particles were subjected to the same tests asExample 38, and the results showed that the conductive connectingelement had a sufficiently low connecting resistivity of 0.008Ω, and aconnecting resistance between the adjacent electrodes was not less than1×10⁹, thereby providing a sufficient line-to-line insulating property.

Cooling and heating cycle tests were carried out 1000 times in the rangeof −40 to 85° C.; however, the connecting resistance virtually showed nochange. Moreover, these tests were carried out as many as 5000 times;however, the connecting resistance virtually showed no change.

Furthermore, the conductive fine particles were immersed into hot waterof 120° C. for 24 hours, and then subjected to the same tests; however,no change was found in the connecting resistivity and the insulatingproperty.

Here, the concentration of the conductive fine particles in theanisotropic conductive paste was gradually increased, and no leakageoccurred between the electrodes until the concentration had reached 25%.

EXAMPLE 42

A nickel coating with a thickness of 0.2 μm was formed by electrolessplating on a divinylbenzene polymer having an average particle size of23 μm, a CV value of 10%, an aspect ratio of 1.2, a K value of 400kgf/mm² and a recovery rate of 60%, with the other factors being thesame as Example 38. Thereafter, gold was plated with a thickness of 0.8μm; thus, conductive fine particles having a plating thickness variationcoefficient of 10%, an average particle size 25 μm, a CV value of 10%,and an aspect ratio of 1.2 were formed.

These conductive fine particles were subjected to the same tests asExample 38, and the results showed that the conductive connectingelement had a sufficiently low connecting resistivity of 0.008Ω, and aconnecting resistance between the adjacent electrodes was not less than1×10⁹, thereby providing a sufficient line-to-line insulating property.

Cooling and heating cycle tests were carried out 1000 times in the rangeof −40 to 85° C.; however, the connecting resistance virtually showed nochange. Moreover, these tests were carried out as many as 5000 times;however, the connecting resistance virtually showed no change.

Furthermore, the conductive fine particles were immersed into hot waterof 120° C. for 24 hours, and then subjected to the same tests; however,no change was found in the connecting resistivity and the insulatingproperty.

Here, the concentration of the conductive fine particles in theanisotropic conductive paste was gradually increased, and no leakageoccurred between the electrodes until the concentration had reached 25%.

EXAMPLE 43

A nickel coating with a thickness of 0.2 μm was formed by electrolessplating on an acrylic copolymer having an average particle size of 23μm, a CV value of 10%, an aspect ratio of 1.09, a K value of 100 kgf/mm²and a recovery rate of 9%, with the other factors being the same asExample 38. Thereafter, gold was plated with a thickness of 0.8 μm;thus, conductive fine particles having a plating thickness variationcoefficient of 10%, an average particle size 25 μm, a CV value of 10%,and an aspect ratio of 1.09 were formed.

These conductive fine particles were subjected to the same tests asExample 38, and the results showed that the conductive connectingelement had a sufficiently low connecting resistivity of 0.01Ω, and aconnecting resistance between the adjacent electrodes was not less than1×10⁹, thereby providing a sufficient line-to-line insulating property.

Cooling and heating cycle tests were carried out 1000 times in the rangeof −40 to 85° C.; however, the connecting resistance virtually showed nochange. Moreover, these tests were carried out as many as 5000 times;and, although the connecting resistivity slightly increased, no problemarose in practical use.

Furthermore, the conductive fine particles were immersed into hot waterof 120° C. for 24 hours, and then subjected to the same tests; however,no change was found in the connecting resistivity and the insulatingproperty.

Here, the concentration of the conductive fine particles in theanisotropic conductive paste was gradually increased, and no leakageoccurred between the electrodes until the concentration had reached 25%.

EXAMPLE 44

A nickel coating with a thickness of 0.2 μm was formed by electrolessplating on silica having an average particle size of 23 μm, a CV valueof 5%, an aspect ratio of 1.04, a K value of 3000 kgf/mm² and a recoveryrate of 90%, with the other factors being the same as Example 38.Thereafter, gold was plated with a thickness of 0.8 μm; thus, conductivefine particles having a plating thickness variation coefficient of 10%,an average particle size of 25 μm, a CV value of 5%, and an aspect ratioof 1.04 were formed.

These conductive fine particles were subjected to the same tests asExample 38, and the results showed that the conductive connectingelement had a sufficiently low connecting resistivity of 0.01Ω, and aconnecting resistance between the adjacent electrodes was not less than1×10⁹, thereby providing a sufficient line-to-line insulating property.

Cooling and heating cycle tests were carried out 1000 times in the rangeof −40 to 85° C.; however, the connecting resistance virtually showed nochange. Moreover, these tests were carried out as many as 5000 times;however, the connecting resistance virtually showed no change.

Furthermore, the conductive fine particles were immersed into hot waterof 120° C. for 24 hours, and then subjected to the same tests; however,no change was found in the connecting resistivity and the insulatingproperty.

Here, the concentration of the conductive fine particles in theanisotropic conductive paste was gradually increased, and no leakageoccurred between the electrodes until the concentration had reached 35%.

EXAMPLE 45

A nickel coating with a thickness of 0.2 μm was formed by electrolessplating on a divinylbenzene polymer having an average particle size of24.5 μm, a CV value of 5%, an aspect ratio of 1.04, a K value of 4000kgf/mm and a recovery rate of 60%, with the other factors being the sameas Example 38. Thereafter, gold was plated with a thickness of 0.1 μm;thus, conductive fine particles having a plating thickness variationcoefficient of 30%, an average particle size of 25 μm, a CV value of 5%,and an aspect ratio of 1.04 were formed.

These conductive fine particles were subjected to the same tests asExample 38, and the results showed that the conductive connectingelement had a sufficiently low connecting resistivity of 0.01Ω, and aconnecting resistance between the adjacent electrodes was not less than1×10⁹, thereby providing a sufficient line-to-line insulating property.

Cooling and heating cycle tests were carried out 1000 times in the rangeof −40 to 85° C.; however, the connecting resistance virtually showed nochange. Moreover, these tests were carried out as many as 5000 times;however, the connecting resistance virtually showed no change.

Furthermore, the conductive fine particles were immersed into hot waterof 120° C. for 24 hours, and then subjected to the same tests; however,no change was found in the connecting resistivity and the insulatingproperty.

Here, the concentration of the conductive fine particles in theanisotropic conductive paste was gradually increased, and no leakageoccurred between the electrodes until the concentration had reached 25%.

EXAMPLE 46

A nickel coating with a thickness of 0.2 μm was formed by electrolessplating on a divinylbenzene polymer having an average particle size of14.5 μm, a CV value of 10%, an aspect ratio of 1.09, a K value of 430kgf/mm² and a recovery rate of 50%, with the other factors being thesame as Example 38. Thereafter, gold was plated with a thickness of 5μm; thus, conductive fine particles having a plating thickness variationcoefficient of 10%, an average particle size 25 μm, a CV value of 10%,and an aspect ratio of 1.09 were formed.

These conductive fine particles were subjected to the same tests asExample 38, and the results showed that the conductive connectingelement had a sufficiently low connecting resistivity of 0.001Ω, and aconnecting resistance between the adjacent electrodes was not less than1×10⁹, thereby providing a sufficient line-to-line insulating property.

Cooling and heating cycle tests were carried out 1000 times in the rangeof −40 to 85° C.; however, the connecting resistance virtually showed nochange. Moreover, these tests were carried out as many as 5000 times;and although the value became 5 times higher than the initial value, theconnecting resistivity was still sufficiently low.

Furthermore, the conductive fine particles were immersed into hot waterof 120° C. for 24 hours, and then subjected to the same tests; however,no change was found in the connecting resistivity and the insulatingproperty.

Here, the concentration of the conductive fine particles in theanisotropic conductive paste was gradually increased, and no leakageoccurred between the electrodes until the concentration had reached 40%.

EXAMPLE 47

A nickel coating with a thickness of 0.2 μm was formed by electrolessplating on a divinylbenzene polymer having an average particle size of23 μm, a CV value of 5%, an aspect ratio of 1.05, a K value of 400kgf/mm² and a recovery rate of 60%, with the other factors being thesame as Example 38. Thereafter, gold was plated with a thickness of 0.8μm by barrel plating; thus, conductive fine particles having a platingthickness variation coefficient of 50%, an average particle size 30 μm,a CV value of 10%, and an aspect ratio of 1.1 were formed.

These conductive fine particles were subjected to the same tests asExample 38, and the results showed that the conductive connectingelement had a sufficiently low connecting resistivity of 0.015Ω, and aconnecting resistance between the adjacent electrodes was not less than1×10⁹, thereby providing a sufficient line-to-line insulating property.

Cooling and heating cycle tests were carried out 1000 times in the rangeof −40 to 85° C.; however, the connecting resistance virtually showed nochange. Moreover, these tests were carried out as many as 5000 times;and a slight increase in the connecting resistivity was seen, but thiswas considered to be within a permissible range of practical use.

Furthermore, the conductive fine particles were immersed into hot waterof 120° C. for 24 hours, and then subjected to the same tests; however,no change was found in the connecting resistivity and the insulatingproperty.

Here, the concentration of the conductive fine particles in theanisotropic conductive paste was gradually increased, and no leakageoccurred between the electrodes until the concentration had reached 25%.

EXAMPLE 48

A nickel coating with a thickness of 0.2 μm was formed by electrolessplating on a divinylbenzene polymer having an average particle size of21.5 μm, a CV value of 5%, an aspect ratio of 1.04, a K value of 400kgf/mm² and a recovery rate of 60%, with the other factors being thesame as Example 38. Thereafter, solder was electroplated with athickness of 5 μm; thus, conductive fine particles having a platingthickness variation coefficient of 10%, an average particle size 32 μm,a CV value of 5%, and an aspect ratio of 1.04 were formed.

These conductive fine particles were subjected to the same tests asExample 38, and the results showed that the conductive connectingelement had a sufficiently low connecting resistivity of 0.002Ω, and aconnecting resistance between the adjacent electrodes was not less than1×10⁹, thereby providing a sufficient line-to-line insulating property.

Cooling and heating cycle tests were carried out 1000 times in the rangeof −40 to 85° C.; however, the connecting resistance virtually showed nochange. Moreover, these tests were carried out as many as 5000 times;however, the connecting resistance virtually showed no change.

Furthermore, the conductive fine particles were immersed into hot waterof 120° C. for 24 hours, and then subjected to the same tests; andalthough the connecting resistivity became 2 times greater than before,no change was found in the insulating property.

Here, the concentration of the conductive fine particles in theanisotropic conductive paste was gradually increased, and no leakageoccurred between the electrodes until the concentration had reached 40%.

EXAMPLE 49

The conductive fine particles obtained in Example 48 were alloy-bondedonto bumps of an IC chip, and after the periphery of the conductive fineparticles had been surrounded by epoxy resin, this was positioned on thebumps on the substrate, and heated and pressed so as to be alloy-bonded.The resulting structural element had a low resistivity in the samemanner as Example 48 with high reliability.

COMPARATIVE EXAMPLE 21

A nickel coating with a thickness of 0.2 μm was formed by electrolessplating on a divinylbenzene polymer having an average particle size of24.5 μm, a CV value of 5%, an aspect ratio of 1.04, a K value of 400kgf/mm² and a recovery rate of 60%, with the other factors being thesame as Example 38. Thereafter, gold was deposited as much as possibleby substitute plating so as to have a thickness of 0.1 μm; thus,conductive fine particles having a plating thickness variationcoefficient of 10%, an average particle size of 25 μm, a CV value of 5%,and an aspect ratio of 1.04 were formed.

These conductive fine particles were subjected to the same tests asExample 38, and the results showed that the conductive connectingelement had a connecting resistivity of 0.04Ω, and it was inferior tothe conductive fine particles of the present invention, but a connectingresistance between the adjacent electrodes was not less than 1×10⁹,thereby providing a sufficient line-to-line insulating property.

Cooling and heating cycle tests were carried out 1000 times in the rangeof −40 to 85° C.; however, the connecting resistance virtually showed nochange. Moreover, these tests were carried out as many as 5000 times;and a significant increase in the connecting resistivity was seen.

Furthermore, the conductive fine particles were immersed into hot waterof 120° C. for 24 hours, and then subjected to the same tests; and nochange was found in the insulating resistivity, but a significantincrease was seen in the connecting resistivity.

Here, the concentration of the conductive fine particles in theanisotropic conductive paste was gradually increased, and no leakageoccurred between the electrodes until the concentration had reached 25%.

COMPARATIVE EXAMPLE 22

A nickel coating with a thickness of 0.05 μm was formed by electrolessplating on a divinylbenzene polymer having an average particle size of0.2 μm, a CV value of 30%, an aspect ratio of 1.1, a K value of 600kgf/mm² and a recovery rate of 40%, with the other factors being thesame as Example 38. Thereafter, gold was electroplated with a thicknessof 0.05 μm; thus, conductive fine particles having a plating thicknessvariation coefficient of 20%, an average particle size of 0.4 μm, a CVvalue of 25%, and an aspect ratio of 1.2 were formed.

These conductive fine particles were subjected to the same tests asExample 38; however, failure in connection occurred in one portion.

COMPARATIVE EXAMPLE 23

A nickel coating with a thickness of 0.2 μm was formed by electrolessplating on a divinylbenzene polymer having an average particle size of6000 μm, a CV value of 5%, an aspect ratio of 1.04, a K value of 300kgf/mm² and a recovery rate of 60%, with the other factors being thesame as Example 38. Thereafter, gold was electroplated with a thicknessof 0.8 μm; thus, conductive fine particles having a plating thicknessvariation coefficient of 10%, an average particle size of 6000 μm, a CVvalue of 5%, and an aspect ratio of 1.04 were formed.

These conductive fine particles were subjected to the same tests asExample 38; however, shortcircuiting occurred due to failure in servingas fine electrodes even in the case of electrode pitches of 3000 μm.

COMPARATIVE EXAMPLE 24

A nickel coating with a thickness of 0.2 μm was formed by electrolessplating on a divinylbenzene polymer having an average particle size of23 μm, a CV value of 60%, an aspect ratio of 1.08, a K value of 400kgf/mm and a recovery rate of 60%, with the other factors being the sameas Example 38. Thereafter, gold was electroplated with a thickness of0.8 μm; thus, conductive fine particles having a plating thicknessvariation coefficient of 20%, an average particle size of 25 μm, a CVvalue of 60%, and an aspect ratio of 1.1 were formed.

These conductive fine particles were subjected to the same tests asExample 38, and the results showed that the conductive connectingelement had a significantly high connecting resistivity of 0.03Ω;however, a connecting resistance between the adjacent electrodes was notless than 1×10⁹, thereby providing a sufficient line-to-line insulatingproperty.

Cooling and heating cycle tests were carried out 1000 times in the rangeof −40 to 85° C.; however, the connecting resistance virtually showed nochange. Moreover, these tests were carried out as many as 5000 times;however, the connecting resistance virtually showed no change.

Furthermore, the conductive fine particles were immersed into hot waterof 120° C. for 24 hours, and then subjected to the same tests; however,no change was found in the connecting resistivity and the insulatingproperty.

Here, when the concentration of the conductive fine particles in theanisotropic conductive paste was gradually increased, current leakageoccurred between the electrodes at the concentration of 15%.

COMPARATIVE EXAMPLE 25

A nickel coating with a thickness of 0.2 μm was formed by electrolessplating on a divinylbenzene polymer having an average particle size of23 μm, a CV value of 15%, an aspect ratio of 1.6, a K value of 400kgf/mm² and a recovery rate of 60%, with the other factors being thesame as Example 38. Thereafter, gold was electroplated with a thicknessof 0.8 μm; thus, conductive fine particles having a plating thicknessvariation coefficient of 10%, an average particle size of 25 μm, a CVvalue of 15%, and an aspect ratio of 1.6 were formed.

These conductive fine particles were subjected to the same tests asExample 38, and the results showed that the conductive connectingelement had a significantly high connecting resistivity of 0.03Ω;however, a connecting resistance between the adjacent electrodes was notless than 1×10⁹, thereby providing a sufficient line-to-line insulatingproperty.

Cooling and heating cycle tests were carried out 1000 times in the rangeof −40 to 85° C.; however, the connecting resistance virtually showed nochange. Moreover, these tests were carried out as many as 5000 times;however, the connecting resistance virtually showed no change.

Furthermore, the conductive fine particles were immersed into hot waterof 120° C. for 24 hours, and then subjected to the same tests; however,no change was found in the connecting resistivity and the insulatingproperty.

Here, when the concentration of the conductive fine particles in theanisotropic conductive paste was gradually increased, current leakageoccurred between the electrodes at the concentration of 15%.

EXAMPLE 50

Nickel particles of 0.4 μm were driven onto nickel balls by using ahybridizer so as to provide protrusions on their surface, and goldplating was then carried out; except these, the same processes asExample 39 were carried out to obtain conductive fine particles. Thesewere then subjected to the same tests, and the results showed that theconductive connecting element had a sufficiently low connectingresistivity of 0.006Ω, and a connecting resistance between the adjacentelectrodes was not less than 1×10⁹, thereby providing a sufficientline-to-line insulating property.

Cooling and heating cycle tests were carried out 1000 times in the rangeof −40 to 85° C.; however, the connecting resistance virtually showed nochange. Here, the concentration of the conductive fine particles in theanisotropic conductive paste was gradually increased, and no leakageoccurred between the electrodes until the concentration had reached 40%.

EXAMPLE 51

The same processes as Example 39 were carried out except thatnickel-gold plated balls were coated with thermoplastic vinyl copolymerresin having a thickness of 1 μm; thus, conductive fine particles wereobtained. These were then subjected to the same tests, and the resultsshowed that the conductive fine particles had a sufficiently lowconnecting resistivity of 0.006Ω, and a connecting resistance betweenthe adjacent electrodes was not less than 1×10⁹, thereby providing asufficient line-to-line insulating property.

Cooling and heating cycle tests were carried out 1000 times in the rangeof −40 to 85° C.; however, the connecting resistance virtually showed nochange. Here, the concentration of the conductive fine particles in theanisotropic conductive paste was gradually increased, and no leakageoccurred between the electrodes until the concentration had reached 60%.

EXAMPLE 52

Nickel-gold plated balls having an average particle size of 8 μm, anaspect ratio of 1.17 and a CV value of 20% were mixed with and dispersedin epoxy resin so that an anisotropic conductive paste was formed. Thiswas applied to a glass-epoxy copper clad substrate (thickness: 1.6 mm,wiring width: 50 μm, electrode pitch: 100 μm) with a virtually uniformthickness by a screen printing method.

On this is superposed a polyimide film substrate (thickness: 30 μm,wiring width: 50 μm, electrode pitch: 100 μm) with a thickness of 100μm, and this was then heated and pressed at 150° C. for two minutes;thus, a conductive connecting element was formed.

This conductive connecting element had a sufficiently low connectingresistivity of 0.006Ω, and a connecting resistance between the adjacentelectrodes was not less than 1×10⁹, thereby providing a sufficientline-to-line insulating property.

Cooling and heating cycle tests were carried out 1000 times in the rangeof −40 to 85° C.; however, the connecting resistance virtually showed nochange. Here, the concentration of the conductive fine particles in theanisotropic conductive paste was gradually increased, however, noleakage occurred between the electrodes until the concentration hadreached 40%.

EXAMPLE 53

The same processes as Example 39 were carried out except thatnickel-palladium plated balls were used so that conductive fineparticles were obtained. These were subjected to the same tests, and theconductive fine particles had a sufficiently low connecting resistivityof 0.007Ω, and a connecting resistance between the adjacent electrodeswas not less than 1×10⁹, thereby providing a sufficient line-to-lineinsulating property.

Cooling and heating cycle tests were carried out 1000 times in the rangeof −40 to 85° C.; however, the connecting resistance virtually showed nochange. Here, the concentration of the conductive fine particles in theanisotropic conductive paste was gradually increased; however, noleakage occurred between the electrodes until the concentration hadreached 40%.

EXAMPLE 54

The same processes as Example 39 were carried out except that the goldplating was carried out by electroplating with a thickness of 0.2 μm sothat conductive fine particles were obtained. These were subjected tothe same tests, and the conductive fine particles had a sufficiently lowconnecting resistivity of 0.007Ω, and a connecting resistance betweenthe adjacent electrodes was not less than 1×10⁹, thereby providing asufficient line-to-line insulating property.

Cooling and heating cycle tests were carried out 1000 times in the rangeof −40 to 85° C.; however, the connecting resistance virtually showed nochange. Here, the concentration of the conductive fine particles in theanisotropic conductive paste was gradually increased; however, noleakage occurred between the electrodes until the concentration hadreached 40%.

EXAMPLE 55

The same processes as Example 39 were carried out except thatcopper-gold plated balls having an aspect ratio of 1.17 and a CV valueof 18% were used, so that conductive fine particles were obtained. Thesewere subjected to the same tests, and the conductive fine particles hada sufficiently low connecting resistivity of 0.005Ω, and a connectingresistance between the adjacent electrodes was not less than 1×10⁹,thereby providing a sufficient line-to-line insulating property.

Cooling and heating cycle tests were carried out 1000 times in the rangeof −40 to 85° C.; however, the connecting resistance virtually showed nochange. Here, the concentration of the conductive fine particles in theanisotropic conductive paste was gradually increased; however, noleakage occurred between the electrodes until the concentration hadreached 35%.

EXAMPLE 56

The same processes as Example 39 were carried out except that metalballs, formed by applying nickel electroless plating with a thickness of0.15 μm to copper having an aspect ratio of 1.17 and a CV value of 18%and then further applying gold plating to this, were used, so thatconductive fine particles were obtained. These were subjected to thesame tests, and the conductive fine particles had a sufficiently lowconnecting resistivity of 0.005Ω, and a connecting resistance betweenthe adjacent electrodes was not less than 1×10⁹, thereby providing asufficient line-to-line insulating property.

Cooling and heating cycle tests were carried out 1000 times in the rangeof −40 to 85° C.; however, the connecting resistance virtually showed nochange. Here, the concentration of the conductive fine particles in theanisotropic conductive paste was gradually increased; however, noleakage occurred between the electrodes until the concentration hadreached 35%.

COMPARATIVE EXAMPLE 26

The same processes as Example 38 were carried out except that nickel(having an aspect ratio of 1.2 and a CV value of 42%, made by INCO Co.,Ltd., Nickel Powder 4SP)-gold plated balls were used, so that conductivefine particles were obtained. These were subjected to the same tests,and the conductive fine particles had an inferior connecting resistivityof 0.025Ω, but a connecting resistance between the adjacent electrodeswas not less than 1×10⁹, thereby providing a sufficient line-to-lineinsulating property.

Cooling and heating cycle tests were carried out 1000 times in the rangeof −40 to 85° C.; however, the connecting resistance virtually showed nochange. Here, the concentration of the conductive fine particles in theanisotropic conductive paste was gradually increased, and currentleakage occurred between the electrodes at the concentration of 30%.

COMPARATIVE EXAMPLE 27

The same processes as Example 38 were carried out except that nickelballs having an aspect ratio of 1.17 and a CV value of 18% were used sothat conductive fine particles were obtained. These were subjected tothe same tests; and the conductive fine particles had a sufficientconnecting resistivity of 0.009Ω, and a connecting resistance betweenthe adjacent electrodes was not less than 1×10⁹, thereby providing asufficient line-to-line insulating property.

Here, the concentration of the conductive fine particles in theanisotropic conductive paste was gradually increased; however, nocurrent leakage occurred between the electrodes until the concentrationhad reached 45%. However, when cooling and heating cycle tests werecarried out 1000 times in the range of −40 to 85° C., the connectingresistance became 10 times greater than the initial value.

COMPARATIVE EXAMPLE 28

The same processes as Example 38 were carried out except that copperballs having an aspect ratio of 1.17 and a CV value of 18% were used sothat conductive fine particles were obtained. These were subjected tothe same tests; and the conductive fine particles had a sufficientconnecting resistivity of 0.006Ω, and a connecting resistance betweenthe adjacent electrodes was not less than 1×10⁹, thereby providing asufficient line-to-line insulating property.

Here, the concentration of the conductive fine particles in theanisotropic conductive paste was gradually increased; however, nocurrent leakage occurred between the electrodes until the concentrationhad reached 40%. However, when cooling and heating cycle tests werecarried out 1000 times in the range of −40 to 85° C., the connectingresistance became 3 times greater than the initial value.

COMPARATIVE EXAMPLE 29

The same processes as Example 38 were carried out except that copperballs having an aspect ratio of 1.17 and a CV value of 18% were used sothat conductive fine particles were obtained. These were subjected tothe same tests; and the conductive fine particles had a sufficientconnecting resistivity of 0.006Ω, and a connecting resistance betweenthe adjacent electrodes was not less than 1×10⁹, thereby providing asufficient line-to-line insulating property.

Here, the concentration of the conductive fine particles in theanisotropic conductive paste was gradually increased; however, nocurrent leakage occurred between the electrodes until the concentrationhad reached 40%. However, when cooling and heating cycle tests werecarried out 1000 times in the range of −40 to 85° C., shortcircuiting,which was supposedly caused by migration, was observed.

COMPARATIVE EXAMPLE 30

The same processes as Example 38 were carried out except that ballswhich were obtained by gold plating onto a crosslinked polystylenepolymer and that had an aspect ratio of 1.05 and a CV value of 8% wereused so that conductive fine particles were obtained. These weresubjected to the same tests; and the conductive fine particles had aninferior connecting resistivity of 0.02Ω, but a connecting resistancebetween the adjacent electrodes was not less than 1×10⁹, therebyproviding a sufficient line-to-line insulating property.

Here, the concentration of the conductive fine particles in theanisotropic conductive paste was gradually increased; and currentleakage occurred when the concentration reached 25%. When cooling andheating cycle tests were carried out 1000 times in the range of −40 to85° C., the connecting resistance virtually showed no change.

COMPARATIVE EXAMPLE 31

The same processes as Example 38 were carried out except thatnickel-gold plated balls having an average particle size of 200 μm, anaspect ratio of 1.05 and a CV value of 8% were used so that conductivefine particles were obtained. These were supposed to be subjected to thesame tests; however, the particles settled in the stage of a bindersolution, failing to provide an anisotropic conductive paste.

COMPARATIVE EXAMPLE 32

The same processes as Example 38 were carried out except thatnickel-gold plating powder of not more than 0.2 μm was used, so thatconductive fine particles were obtained. These were supposed to besubjected to the same tests; however, poor connection occurred in someplaces even though the concentration of the powder increased, resultingin failure to carry out the tests.

EXAMPLE 57

(A) Production of Base Particles

Divinylbenzene were polymerized by a suspension polymerization method,and this was then classified by a wet-method to produce base particles.These base particles had an average particle size of 100 μm, a standarddeviation of 0.98 μm and a CV value of 0.98%.

(B) Production of Conductive Fine Particles by the Formation of aConductive Metal Layer

Next, the base particles were subjected to an electroless nickel platingprocess as a pre-treatment for the base particles so that a nickelplating layer of 0.15 μm was formed on the surface of each of the baseparticles.

Successively, after completion of the pre-treatment, the base particleswere immersed in a plating bath containing nickel chloride, nickelsulfate and boric acid so as to carry out electroplating by using aflow-through plater (produced by Uemura Kogyo K.K.); thus, conductivefine particles having three types of conductive metal layers, that is,nickel thicknesses of 2, 5 and 13 μm, were produced.

(C) Application of the Conductive Fine Particles onto an IC Chip

An IC chip (wafer), which had electrode sections comprising platednickel and plated copper on aluminum, with electrode pitches of 150 μm(peripheral arrangement) and 200 pins, was used, and silver paste(silver flake/epoxy adhesive) was formed with a thickness of 10 μm onthe electrode sections of this IC chip by using the screen printing.

Next, by using a ball mounter produced by Nittetsu Micro K.K., ballswere sucked onto ball suction holes in a mold provided with ball suctionholes having a diameter of 30 μm at positions corresponding to theelectrodes of the IC chip; thus, the balls were placed on the electrodesections of the IC chip.

Thereafter, the conductive fine particles were secured to the electrodesections of the IC chip (wafer) by heating at 130° C. for five minutes,and by cutting the wafer so that the IC chips (wafer) were divided intoits chip size.

(D) Connection and Securing of the IC Chip onto a Substrate

Next, a glass-epoxy substrate in which electrode sections were formed byelectroless copper plating at positions corresponding to the electrodesections of the IC chip was used, and after a silver paste printingprocess had been carried out on the electrode sections of theglass-epoxy substrate, the IC chip on which the conductive fineparticles had been secured was secured thereon by heat by using abonding device.

Evaluation

With respect to the glass-epoxy substrate on which the base particles,the conductive fine particles and the IC chip were connected andsecured, obtained in Example 57, the following evaluation tests werecarried out to evaluate the characteristics thereof. Table 12 shows theresults of the tests.

(1) Thermal Conductivity of the Base Particles

A sheet having a thickness of 1.0 mm and comprising the same material asthe base particles was prepared, and the thermal conductivity wasmeasured thereon by using a quick thermal conductivity meter (producedby Kyoto Denshisha K.K., Type QTM-D3).

(2) Tensile Strength of the Conductive Metal Layer

A film-shaped sample having a thickness of 0.5 mm was manufactured underthe same conditions as the plating process onto the base particles, andthis was subjected to measurements at a tension speed of 10 mm/min byusing a tension tester (made by Simadzu Corporation, Autograph).

(3) Evaluation on Bonding Strength of the Conductive Fine Particles tothe IC Chip (Wafer)

By using a bonding tester (produced by Leska K.K. PTR-10 Type) as atesting device, strain deformation tests were carried out at a straindislocation speed of 0.05 mm/sec with a location of 30 μm; thus, theamount of recoverable elastic strain and the strength against separationof the IC chip (wafer) from the electrode section due to straindeformation of the conductive fine particles were found.

(4) Heat Resistance Test

By using a Perfect Oven produced by Tabai Seisakusho K.K. was used as atesting device, tests were carried out at 200° C. for 500 hours toexamine the electrical bonding state.

(5) Heat Cycle Test

By using a heat cycle tester produced by Kondo Kagakusha K.K. as atesting device, heat cycles, each setting 30-minute hold at 160° C. and30-minute hold at −40° C., were repeated 1000 times, and the electricalconnecting state of the connecting section was then examined.

(6) Limiting Current Value Test

An electric current was allowed to flow while the applied voltage acrossthe electrodes was gradually increased by using a dc-stabilized powersource so that the current at the limited point on the voltage-currentstraight line was found.

EXAMPLE 58

(A) Production of Base Particles

The same processes as Example 57 were carried out except thatdivinylbenzene manufactured had an average particle size of 50 μm, astandard deviation of 0.53 μm and a CV value of 1.06%.

(B) Production of Conductive Fine Particles by the Formation of aConductive Metal Layer

Next, the base particles were subjected to a pre-treatment in the samemanner as Example 57, and a nickel plating layer of 0.15 μm was formedon the surface of each of the base particles.

Successively, after completion of the pre-treatment, the base particleswere immersed in a plating bath containing potassium gold cyanide tocarry out electroplating by using the same plating device as Example 57;thus, conductive fine particles were manufactured by forming aconductive metal layer having a gold thickness of 2 μm.

(C) Application of the Conductive Fine Particles onto an IC Chip andConnection and Securing of the IC Chip to the Substrate

The same processes as Example 57 were carried out.

Evaluation

With respect to the glass-epoxy substrate on which the base particles,the conductive fine particles and the IC chip were connected andsecured, the same evaluation tests as Example 57 were carried out. Table12 shows the results of the tests.

EXAMPLE 59

(A) Production of Conductive Fine Particles by Formation of a ConductiveMetal Layer and a Low-Melting-Point Metal Layer

The same base particles as Example 57 was used and subjected toelectroless nickel plating. Further, by using the same plating deviceand plating bath as Example 57, particles having a conductive metallayer composed of nickel with a thickness of 5 μm were manufactured.Then, these particles were immersed in a solder plating bath (producedby Okuno Selyaku Kogyo K.K., Toptina M S), comprising an acidicbrightening bath, to carry out an electroplating process; thus, alow-melting-point metal layer comprising an eutectic solder layer with athickness of 10 μm and a composition of tin 63 weight %/lead 37 weight %was formed around each of the fine particles, thereby preparingconductive fine particles.

(B) Application of the Conductive Fine Particles onto an IC Chip andConnection and Securing of the IC Chip to the Substrate

The conductive fine particles were applied onto the IC chip in the samemanner as Example 57, and the conductive fine particles were connectedand secured to the electrode sections of the IC chip (wafer) by heatingat 230° C. for 10 seconds, and the IC chip (wafer) was cut into its chipsize.

Thereafter, the IC chip was connected and secured to the substrate inthe same manner as Example 57.

Evaluation

With respect to the glass-epoxy substrate on which the base particles,the conductive fine particles and the IC chip were connected andsecured, the same evaluation tests as Example 57 were carried out. Table12 shows the results of the tests.

EXAMPLE 60

(A) Production of Base Particles

First, after styrene and methaacryloxytriethoxysilane (6 to 4 weightratio) were copolymerized by using a suspension polymerization method,alcoxysilyl groups were subjected to a hydrolysis reaction with eachother so as to be crosslinked, and this was classified by a wet-methodso that base particles were manufactured. These base particles had anaverage particle size of 95 μm, a standard deviation of 0.79 μm and a CVvalue of 0.83%.

(B) Production of Conductive Fine Particles by the Formation of aConductive Metal Layer and a Low-Melting-Point Metal Layer

Next, the base particles were subjected to a pre-treatment in the samemanner as Example 57, and a nickel plating layer of 2 μm was formed onthe surface of each of the base particles. Moreover, the same processesas Example 3 were carried out so that a low-melting-point metal layercomprising an eutectic solder plating layer with a thickness of 10 μmwas formed, thereby preparing conductive fine particles.

(C) Application of the Conductive Fine Particles onto an IC Chip andConnection and Securing of the IC Chip to the Substrate

After the conductive fine particles were applied to the IC chip in thesame manner as Example 57, this was heated at 210° C. for one minute sothat the conductive fine particles were connected and secured to theelectrode sections of the IC chip (wafer), and the IC chip (wafer) wasthen cut into its chip size.

Thereafter in the same manner as Example 57, the chip was connected andsecured to the substrate.

Evaluation

With respect to the glass-epoxy substrate on which the base particles,the conductive fine particles and the IC chip were connected andsecured, the same evaluation tests as Example 57 were carried out. Table12 shows the results of the tests.

EXAMPLE 61

(A) Production of Base Particles

First, a polymer in which 10% by weight of titanium oxide whisker wasuniformly blended in a divinylbenzene polymer was manufactured by usinga suspension polymerization method, and this was classified by awet-method so that base particles were manufactured. These baseparticles had an average particle size of 103 μm, a standard deviationof 1.34 μm and a CV value of 1.3%.

(B) Production of Conductive Fine Particles by the Formation of aConductive Metal Layer and a Low-Melting-Point Metal Layer

In the same manner as Example 60, a conductive metal layer whichcomprises a nickel plating layer of 2 μm and a low-melting-point metallayer comprising an eutectic solder plating layer with a thickness of 10μm were formed, thereby preparing conductive fine particles.

(C) Application of the Conductive Fine Particles onto an IC Chip andConnection and Securing of the IC Chip to the Substrate

In the same manner as Example 4, the application of the conductive fineparticles to the IC chip and the connection and securing of the IC chiponto the substrate were carried out.

Evaluation

With respect to the glass-epoxy substrate on which the base particles,the conductive fine particles and the IC chip were connected andsecured, the same evaluation tests as Example 57 were carried out. Table12 shows the results of the tests.

EXAMPLE 62

(A) Production of Base Particles

The same base particles as manufactured in Example 57 were used.

(B) Production of Conductive Fine Particles by the Formation of aConductive Metal Layer and a Low-Melting-Point Metal Layer

Next, in the same manner as Example 57, the base particles weresubjected to a pre-treatment, and a conductive metal layer having anickel thickness of 5 μm was prepared.

By using the same plating device as Example 57, the base particleshaving the conductive metal layer were immersed in a plating bathcontaining tin pyrophosphate and silver iodide so as to carry out anelectroplating process; thus, a low-melting-point metal layer comprisingan eutectic solder layer that had a thickness of 12 μm and a compositionof tin 96.5 weight %/silver 3.5 weight % was formed around each of thefine particles, thereby preparing conductive fine particles.

(C) Application of the Conductive Fine Particles onto an IC Chip andConnection and Securing of the IC Chip to the Substrate

In the same manner as Example 4, the application of the conductive fineparticles to the IC chip and the connection and securing of the IC chiponto the substrate were carried out.

Evaluation

With respect to the glass-epoxy substrate on which the base particles,the conductive fine particles and the IC chip were connected andsecured, the same evaluation tests as Example 57 were carried out. Table12 shows the results of the tests.

EXAMPLE 63

(A) Production of Base Particles

The base particles were manufactured in the same manner as Example 57.

(B) Production of Conductive Fine Particles by the Formation of aConductive Metal Layer and a Low-Melting-Point Metal Layer

Next, in the same manner as Example 57, the base particles weresubjected to a pre-treatment, and a conductive metal layer having anickel thickness of 5 μm was prepared.

By using the same plating device as Example 57, the base particleshaving the conductive metal layer were immersed in a plating bathcontaining methasulfonic acid and bismuth methasulfonate to carry out anelectroplating process; thus, a low-melting-point metal layer comprisingan eutectic solder layer that had a thickness of 10 μm and a compositionof tin 92.5 weight %/bismuth 7.5 weight % was formed around each of thefine particles, thereby preparing conductive fine particles.

(C) Application of the Conductive Fine Particles onto an IC Chip andConnection and Securing of the IC Chip to the Substrate

In the same manner as Example 4, the application of the conductive fineparticles to the IC chip and the connection and securing of the IC chiponto the substrate were carried out.

Evaluation

With respect to the glass-epoxy substrate on which the base particles,the conductive fine particles and the IC chip were connected andsecured, the same evaluation tests as Example 57 were carried out. Table12 shows the results of the tests.

EXAMPLE 64

(A) Production of Base Particles

The base particles were manufactured in the same manner as Example 57.

(B) Production of Conductive Fine Particles by the Formation of aConductive Metal Layer and a Low-Melting-Point Metal Layer

Next, in the same manner as Example 57, the base particles weresubjected to a pre-treatment, and after completion of the tre-treatment,the base particles were subjected to an electroplating process to thepre-treated base particles by using the same plating device as Example57 so that a conductive metal layer having a copper thickness of 8 μmwas prepared.

Then, the base particles having the conductive metal layer were immersedin a plating bath containing bismuth methasulfonate to carry out anelectroplating process; thus, a low-melting-point metal layer comprisingbismuth with a thickness of 1 μm was formed. Further, this was subjectedto an electroplating process using a plating bath containing tinpyrophosphate and silver iodide; thus, a low-melting-point metal layercomprising an eutectic solder layer that had a thickness of 10 μm and acomposition of tin 96.5 weight %/silver 3.5 weight % was formed on thelow-melting-point metal layer comprising bismuth, thereby preparingconductive fine particles.

(C) Application of the Conductive Fine Particles onto an IC Chip andConnection and Securing of the IC Chip to the Substrate

In the same manner as Example 60, the application of the conductive fineparticles to the IC chip, the connection and securing of the IC chiponto the substrate were carried out.

Evaluation

With respect to the glass-epoxy substrate on which the base particles,the conductive fine particles and the IC chip were connected andsecured, the same evaluation tests as Example 57 were carried out. Table12 shows the results of the tests.

EXAMPLE 65

(A) Production of Base Particles

First, divinylbenzene was polymerized by a suspension polymerizationmethod, and this was classified by a wet-method so that base particleswere manufactured. These base particles had an average particle size of300 μm, a standard deviation of 2.90 μm and a CV Value of 0.97%.

(B) Production of Conductive Fine Particles by the Formation of aConductive Metal Layer and a Low-Melting-Point Metal Layer

Next, the base particles were subjected an electroless nickel platingprocess as a pre-treatment so that a nickel plating layer of 0.3 μm wasformed on the surface of each of the base particles.

Then, by using the same plating device as Example 57, the base particlesafter completion of the pre-treatment were immersed in a plating bathcontaining nickel chloride, nickel sulfate and boric acid to carry outan electroplating process; thus, a conductive metal layer having anickel thickness of 30 μm was formed.

Next, the base particles having the conductive metal layer weresubjected to an electroplating process so that a low-melting-point metallayer comprising an eutectic solder layer that had a thickness of 25 μmand a composition of tin 63 weight %/lead 37 weight % was formed,thereby preparing conductive fine particles.

(C) Application of the Conductive Fine Particles onto an IC Chip andConnection and Securing of the IC Chip to the Substrate

In the same manner as Example 4, the application of the conductive fineparticles to the IC chip, the connection and securing of the IC chiponto the substrate were carried out.

Evaluation

With respect to the glass-epoxy substrate on which the base particles,the conductive fine particles and the IC chip were connected andsecured, the same evaluation tests as Example 57 were carried out. Table12 shows the results of the tests.

EXAMPLE 66

(A) Production of Base Particles

First, divlnylbenzene was polymerized by a suspension polymerizationmethod, and this was classified by a wet-method so that base particleswere manufactured. These base particles had an average particle size of650 μm, a standard deviation of 4.88 μm and a CV value of 0.75%.

(B) Production of Conductive Fine Particles by the Formation of aConductive Metal Layer and a Low-Melting-Point Metal Layer

Next, the base particles were subjected an electroless nickel platingprocess as a pre-treatment so that a nickel plating layer of 0.3 μm wasformed on the surface of each of the base particles.

Then, by using the same plating device as Example 57, the base particlesafter completion of the pre-treatment were immersed in a plating bathcontaining nickel chloride, nickel sulfate and boric acid to carry outan electroplating process; thus, a conductive metal layer having anickel thickness of 55 μm was formed.

Next, the base particles having the conductive metal layer weresubjected to an electroplating process so that a low-melting-point metallayer comprising an eutectic solder layer that had a thickness of 50 μmand a composition of tin 63 weight %/lead 37 weight % was formed,thereby preparing conductive fine particles.

(C) Application of the Conductive Fine Particles onto an IC Chip andConnection and Securing of the IC Chip to the Substrate

In the same manner as Example 60, the application of the conductive fineparticles to the IC chip, the connection and securing of the IC chiponto the substrate were carried out.

Evaluation

With respect to the glass-epoxy substrate on which the base particles,the conductive fine particles and the IC chip were connected andsecured, the same evaluation tests as Example 57 were carried out. Table12 shows the results of the tests.

EXAMPLE 67

(A) Production of Base Particles

The same base particles as Example 57 were used.

(B) Production of Conductive Fine Particles by the Formation of aConductive Metal Layer and a Low-Melting-Point Metal Layer

Next, in the same manner as Example 57, the base particles weresubjected to a pre-treatment by electroless plating, with the resultthat an electroless nickel plating layer having a thickness of 0.15 μmwas formed. Then, the base particles after completion of thepre-treatment was subjected to an electroplating process in the samemanner as Example 8 so that a metal layer comprising copper which athickness of 8 μm was prepared. This was coated with a nickel platinglayer of 1 μm by electroplating. Moreover, this was coated with alow-melting-point metal layer which comprises a solder layer composed oftin 96.5 weight %/silver 3.5 weight % and which has a thickness of 10 μmin the same manner as Example 6 so that conductive fine particles wereprepared.

(C) Application of the Conductive Fine Particles onto an IC Chip andConnection and Securing of the IC Chip to the Substrate

In the same manner as Example 60, the application of the conductive fineparticles to the IC chip, the connection and securing of the IC chiponto the substrate were carried out.

Evaluation

With respect to the glass-epoxy substrate on which the base particles,the conductive fine particles and the IC chip were connected andsecured, the same evaluation tests as Example 57 were carried out. Table12 shows the results of the tests.

EXAMPLE 68

(A) Production of Base Particles

The same base particles as Example 57 were used.

(B) Production of Conductive Fine Particles by the Formation of aConductive Metal Layer and a Low-Melting-Point Metal Layer

Next, in the same manner as Example 57, the base particles weresubjected to a pre-treatment by electroless plating, with the resultthat an electroless nickel plating layer having a thickness of 0.15 μmwas formed. Then, the base particles after completion of thepre-treatment was subjected to an electroplating process in the samemanner as Example 2 to form a conductive metal layer comprising goldhaving a thickness of 8 μm; thus, conductive fine particles wereprepared.

(C) Application of the Conductive Fine Particles onto an IC Chip andConnection and Securing of the IC Chip to the Substrate

By using the same ball mounter as Example 57, the conductive fineparticles were placed on the electrodes of an IC chip, and theconductive fine particles were then pressed onto the electrode sectionswith heat by a bonding machine at 300% while applying ultrasonic waves.

(D) Connection and Securing of the IC Chip to the Substrate

The IC chip to which the conductive fine particles had been connectedand secured was connected and secured to a glass-epoxy substrate in thesame manner as Example 57.

Evaluation

With respect to the glass-epoxy substrate on which the base particles,the conductive fine particles and the IC chip were connected andsecured, the same evaluation tests as Example 57 were carried out. Table12 shows the results of the tests.

COMPARATIVE EXAMPLE 32

(A) Conductive Fine Particles

Particles, which comprises high-melting-point solder particles having anaverage particle size of 78 μm and comprising tin 10 weight %/lead 90weight %, and formed thereon, an eutectic solder plating having athickness of 10 μm and comprising tin 63 weight %/lead 37 weight %, wereused as the conductive fine particles. The standard deviation thereofwas 0.9 μm.

(B) Application of the Conductive Fine Particles onto an IC Chip andConnection and Securing of the IC Chip to the Substrate

The conductive fine particles were applied onto the IC chip in the samemanner as Example 57, and the conductive fine particles were connectedand secured to the electrode sections of the IC chip (wafer) by heatingat 230° C. for 10 seconds, and the IC chip (wafer) was cut into its chipsize.

Thereafter, the IC chip was connected and secured to the substrate inthe same manner as Example 57.

Evaluation

With respect to the glass-epoxy substrate to which the IC chip wasconnected and secured by using the conductive fine particles, evaluationtests were carried out. As a result, separation occurred at connectingsections between the conductive fine particles and the IC chip, andafter the heat cycle tests of 450 times, a failure occurred inconduction.

COMPARATIVE EXAMPLE 33

(A) Conductive Fine Particles

Particles, which comprises copper balls having an average particle sizeof 80 μm, and formed thereon, a gold plating layer having a thickness of7 μm were used as the conductive fine particles. The standard deviationthereof was 1.1 μm.

(B) Application of the Conductive Fine Particles onto an IC Chip andConnection and Securing of the IC Chip to the Substrate

The conductive fine particles were applied onto the IC chip in the samemanner as Example 57, and the conductive fine particles were connectedand secured to the electrode sections of the IC chip (wafer) by heatingat 230° C. for 10 seconds, and the IC chip (wafer) was cut into its chipsize.

Thereafter, the IC chip was connected and secured to the substrate inthe same manner as Example 57.

Evaluation

With respect to the glass-epoxy substrate to which the IC chip wasconnected and secured by using the conductive fine particles, evaluationtests were carried out. As a result, separation occurred at connectingsections between the conductive fine particles and the IC chip, andafter the heat cycle tests of 550 times, a failure occurred inconduction.

COMPARATIVE EXAMPLE 34

(A) Production of Base Particles

The same base particles as manufactured in Example 57 were used.

(B) Production of Conductive Fine Particles by the Formation of aConductive Metal Layer

The base particles were subjected to a pre-treatment in the same manneras Example 57, and a nickel plating layer having a thickness of 0.8 μmwas formed thereon by electroplating; thus, conductive fine particleswere manufactured.

(C) Application of the Conductive Fine Particles onto an IC Chip andConnection and Securing of the IC Chip to the Substrate

The conductive fine particles were placed on the electrode sections ofthe IC chip, and connected and secured thereto under the same conditionsas Example 57.

Evaluation

With respect to the glass-epoxy substrate to which the base particles,the conductive fine particles and the IC chip were connected andsecured, evaluation tests were carried out in the same manner as Example57. As a result, cracks took place in the conductive metal layer due toheat; consequently, after the heat resistance test of 50 hours, afailure occurred in conduction. Moreover, after the heat cycle tests of170 times, a failure occurred in conduction.

COMPARATIVE EXAMPLE 35

(A) Production of Base Particles

The same base particles as manufactured in Example 57 were used.

(B) Production of Conductive Fine Particles by the Formation of aConductive Metal Layer

The base particles were subjected to a pre-treatment in the same manneras Example 57, and a nickel plating layer having a thickness of 2.5 μmwas formed thereon by electroplating; thus, conductive fine particleswere manufactured.

(C) Application of the Conductive Fine Particles onto an IC Chip andConnection and Securing of the IC Chip to the Substrate

The conductive fine particles were placed on the electrode sections ofthe IC chip, and connected and secured thereto under the same conditionsas Example 57.

Evaluation

With respect to the glass-epoxy substrate to which the base particles,the conductive fine particles and the IC chip were connected andsecured, evaluation tests were carried out in the same manner as Example57. As a result, the results of the heat resistance test was good;however, after the heat cycle tests of 350 times, a failure occurred inconduction.

COMPARATIVE EXAMPLE 36

(A) Production of Base Particles

The same base particles as manufactured in Example 57 were used.

(B) Production of Conductive Fine Particles by the Formation of aConductive Metal Layer

The base particles were allowed to adsorb a catalyst comprising atin/palladium double salt on their surface, and these were treated witha sulfuric acid solution to be activated. A nickel layer having athickness of 0.9 μm was formed on the surface thereof by electrolessplating so that conductive fine particles were manufactured.

(C) Application of the Conductive Fine Particles onto an IC Chip andConnection and Securing of the IC Chip to the Substrate

The conductive fine particles were placed on the electrode sections ofthe IC chip, and connected and secured thereto under the same conditionsas Example 57.

Evaluation

With respect to the glass-epoxy substrate to which the base particles,the conductive fine particles and the IC chip were connected andsecured, evaluation tests were carried out in the same manner as Example57. As a result, after the heat resistance test of 270 hours, crackstook place in the nickel plating layer, resulting in failure inconduction. Moreover, after the heat cycle tests of 560 times, a failureoccurred in conduction.

COMPARATIVE EXAMPLE 37

(A) Production of Base Particles

The same base particles as Example 57 were used.

(B) Production of Conductive Fine Particles by the Formation of aConductive Metal Layer and a Low-Melting-Point Metal Layer

Next, in the same manner as Example 57, the base particles weresubjected to a pre-treatment by electroless plating, with the resultthat an electroless nickel plating layer having a thickness of 0.15 μmwas formed. Then, the base particles after completion of thepre-treatment was subjected to an electroplating process in the samemanner as Example 57 so as to form a conductive metal layer comprisingnickel with a thickness of 5 μm. Moreover, this was coated with eutecticsolder plating with a thickness of 53 μm and comprising tin 63 weight%/lead 37 weight % in the same manner as Example 3; thus, particles wereprepared. The standard deviation was 2.3 μm.

(C) Application of the Conductive Fine Particles onto an IC Chip AndConnection and Securing of the IC Chip to the Substrate

The conductive fine particles were placed on the IC chip, and the ICchip was connected and secured to the substrate in the same manner asExample 3.

Evaluation

With respect to the glass-epoxy substrate to which the base particles,the conductive fine particles and the IC chip were connected andsecured, evaluation tests were carried out in the same manner as Example57. As a result, the results of the heat resistance test was good;however, after the heat cycle tests of 750 times, a failure occurred inconduction.

COMPARATIVE EXAMPLE 38

(A) Production of Base Particles

The same base particles as Example 57 were used.

(B) Production of Conductive Fine Particles by the Formation of aConductive Metal Layer and a Low-Melting-Point Metal Layer

Next, in the same manner as Example 57, the base particles weresubjected to a pre-treatment by an electroless plating, with the resultthat an electroless nickel plating layer with a thickness of 0.15 μm wasformed. Then, the base particles after completion of the pre-treatmentwas subjected to an electroplating process in the same manner as Example57 to form a conductive metal layer comprising nickel having a thicknessof 5 μm. Moreover, this was coated with eutectic solder plating having athickness of 2.5 μm and comprising tin 63 weight %/lead 37 weight % inthe same manner as Example 3; thus, particles were prepared. Thestandard deviation was 1.7 μm.

(C) Application of the Conductive Fine Particles onto an IC Chip andConnection and Securing of the IC Chip to the Substrate

The conductive fine particles were placed on the IC chip, and the ICchip was connected and secured to the substrate in the same manner asExample 59.

Evaluation

With respect to the glass-epoxy substrate to which the base particles,the conductive fine particles and the IC chip were connected andsecured, evaluation tests were carried out in the same manner as Example57. As a result, since the solder plating layer was thin, the limitedcurrent value was as low as 0.4 Amp. Moreover, after the heat cycletests of 750 times, a failure occurred in conduction. TABLE 12Evaluation of conductive particles Thermal Evaluation of electroniccircuit part conductivity of Tensile strength Connection stateConnection state base particles of conductive Peel strength after heatafter heat cycle Limiting current (W/mK) metal layer (kg/mm²) (gr)resistance test test value test (A) Ex. 57 0.12 85 38 Good Good 4 Ex. 580.12 23 35 Good Good 5 Ex. 59 0.12 85 38 Good Good 4.5 Ex. 60 0.36 85 34Good Good 3.6 Ex. 61 0.32 85 45 Good Good 5 Ex. 62 0.12 85 50 Good Good3.8 Ex. 63 0.12 85 43 Good Good 4.8 Ex. 64 0.12 — 57 Good Good 4.5 Ex.65 0.12 85 350 Good Good 8 Ex. 66 0.12 85 1150 Good Good 8 Ex. 67 0.12 —55 Good Good 5 Ex. 68 0.12 23 30 Good Good 5

INDUSTRIAL APPLICABILITY

As described above, in the manufacturing device for conductive fineparticles of the present invention, even if the number of revolutions ofthe treatment chamber is increased, no overflow occurs, and the amountof flow from the porous member is increased; therefore, plating isuniformly carried out even on particles having a size not more than 100μm. Moreover, even in the case of a large particle size of not less than100 μm, since the amount of a plating solution inside the treatmentchamber is increased and a high current density is obtained, it ispossible to shorten the plating time. Moreover, a sheet-shaped filter isaffixed on the inner side face of the porous member so that clogging ofparticles is not occurred and consequently to increase the number ofapplications thereof. The sheet-shaped filter is more inexpensive thanthe porous member of plastic, ceramics or the like, and it results incutting costs. Furthermore, the application of a plate-shaped porousmember contributes to avoid aggregation of fine particles without addingdummy chips; therefore, it is possible to obtain clean conductive fineparticles free from scratches and dents on the plating surface thereof,and also to omit the separation process between the dummy chips and thefine particles. Accordingly, the manufacturing device for conductivefine particles of the present invention is particularly effective whenapplied to cases in which plating is carried out on metal which tends toaggregate and has a soft coat film, such as solder plating.

The manufacturing method for conductive fine particles of the presentinvention has a superior stirring effect so that aggregated lumps,caused at the time of extended power application time or a high currentdensity, can be pulverized; thus, it is possible to form a uniformplating layer with high efficiency.

In the manufacturing method for conductive fine particles of the presentinvention, even in the case that fine particles are relatively small, itis possible to form a uniform plating layer effectively on all the fineparticles, by controlling the film thickness of the conductive baselayer by means of an electroless plating, adjusting the specific gravityof the plating solution or the like.

The conductive fine particles of the present invention can provide ananisotropic conductive adhesive that has a greater current capacity uponconnection and high reliability in connecting processes, and is freefrom current leakage.

The electronic circuit part of the present invention makes it possibleto systematically eliminate poor connection, etc. resulting from variousreasons between the electronic circuit element and the electroniccircuit substrate, and also to minimize the connection pitches;therefore, it contributes to solve various conventional problems byusing, for example, electronic circuit elements and electronic circuitsubstrates with high-density wiring.

1. A laminated conductive fine particle provided with a conductive metal layer on the surface of a spherical elastic base particle and further provided with a low-melting-point metal layer on the surface of the conductive metal layer, wherein the conductive metal layer is formed by at least one element selected from the group consisting of nickel, palladium, gold, silver, copper, platinum and aluminum, wherein the low-melting-point metal layer is formed by at least one element having a melting point of not more than 260° C. selected from the group consisting of tin, lead, bismuth, silver, zinc, indium, and copper.
 2. The laminated conductive fine particle according to claim 1, wherein the thickness (t; unit mm) of the conductive metal layer is set in a range represented by formula [1] P×D/σ<t<0.2×D  [formula 1] where P is a constant of pressure unit, 0.7 Kg/mm², D is the diameter (unit:mm) of an elastic base particle, and σ is a tensile strength (unit:Kg/mm²) of metal material forming the conductive metal layer which is measured under the condition that a sheet shaped from the metal material having a thickness of 0.5 to 2 mm is tested at a tensile speed of 10 mm/mm by tensile tester.
 3. The laminated conductive fine particle according to claim 1, wherein the low-melting-point metal layer has a thickness of not more than 50% of the diameter of the elastic base particles.
 4. The laminated conductive fine particle according to claim 1, wherein the low-melting-point metal layer has a thickness of not less than 3% of the diameter of the elastic base particles.
 5. The laminated conductive fine particle according to claim 1, wherein the spherical elastic base particle have a thermal conductivity of not less than 0.30 W/m K.
 6. The laminated conductive fine particle according to claim 1, wherein the spherical elastic base particle is a resin material or an organic/inorganic hybrid material.
 7. The laminated conductive fine particle according to claim 1, wherein the spherical elastic base particle further includes an inorganic filler. 